user38721: I want to burn the arduino optiboot_atmega328.hex bootloader but it doesn't work. I remember that I was able to burn the BL using the arduino IDE which was quite easy, this time I'm having some problems.
I'm always using an avrispv2 programmer to flash my atmegas and it was also this programmer I used once to burn the BL. When I try, the IDE gives the following output:
avrdude: Version 6.3-20171130
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2014 Joerg Wunsch

         System wide configuration file is "/home/xxx/Downloads/arduino-1.8.7-linux64/arduino-1.8.7/hardware/tools/avr/etc/avrdude.conf"
         User configuration file is "/home/xxx/.avrduderc"
         User configuration file does not exist or is not a regular file, skipping

         Using Port                    : /dev/ttyACM2
         Using Programmer              : stk500v1
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x00

avrdude done.  Thank you.

Fehler beim Brennen des Bootloaders.

After this didn't work I tried to manually upload the optiboot_atmega328.hex with avrdude on the commandline (following this guide). The output of avrdude is as follows:
avrdude -b 19200 -c avrispv2 -p m328p -v -e -U efuse:w:0x05:m -U hfuse:w:0xD6:m -U lfuse:w:0xFF:m -P /dev/ttyACM2

avrdude: Version 6.3
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2014 Joerg Wunsch

         System wide configuration file is "/etc/avrdude.conf"
         User configuration file is "/home/tabaluga/.avrduderc"
         User configuration file does not exist or is not a regular file, skipping

         Using Port                    : /dev/ttyACM2
         Using Programmer              : avrispv2
         Overriding Baud Rate          : 19200
         AVR Part                      : ATmega328P
         Chip Erase delay              : 9000 us
         PAGEL                         : PD7
         BS2                           : PC2
         RESET disposition             : dedicated
         RETRY pulse                   : SCK
         serial program mode           : yes
         parallel program mode         : yes
         Timeout                       : 200
         StabDelay                     : 100
         CmdexeDelay                   : 25
         SyncLoops                     : 32
         ByteDelay                     : 0
         PollIndex                     : 3
         PollValue                     : 0x53
         Memory Detail                 :

                                  Block Poll               Page                       Polled
           Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
           ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
           eeprom        65    20     4    0 no       1024    4      0  3600  3600 0xff 0xff
           flash         65     6   128    0 yes     32768  128    256  4500  4500 0xff 0xff
           lfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           hfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           efuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           lock           0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           calibration    0     0     0    0 no          1    0      0     0     0 0x00 0x00
           signature      0     0     0    0 no          3    0      0     0     0 0x00 0x00

         Programmer Type : STK500V2
         Description     : Atmel AVR ISP V2
         Programmer Model: STK500
         Hardware Version: 10
         Firmware Version Master : 2.10
avrdude: stk500v2_command(): command failed
avrdude: stk500v2_getparm(): failed to get parameter 0x9a
         Topcard         : Unknown
         Vtarget         : 3.3 V
         SCK period      : 17.4 us
         Varef           : 3.3 V
         Oscillator      : Off

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x1e950f (probably m328p)
avrdude: safemode: hfuse reads as D9
avrdude: safemode: efuse reads as FD
avrdude: erasing chip
avrdude: reading input file "0x05"
avrdude: writing efuse (1 bytes):

Writing | ################################################## | 100% 0.01s

avrdude: 1 bytes of efuse written
avrdude: verifying efuse memory against 0x05:
avrdude: load data efuse data from input file 0x05:
avrdude: input file 0x05 contains 1 bytes
avrdude: reading on-chip efuse data:

Reading | ################################################## | 100% 0.00s

avrdude: verifying ...
avrdude: verification error, first mismatch at byte 0x0000
         0xfd != 0x05
avrdude: verification error; content mismatch

avrdude: safemode: hfuse reads as D9
avrdude: safemode: efuse reads as FD
avrdude: safemode: efuse changed! Was 5, and is now fd
Would you like this fuse to be changed back? [y/n] y
avrdude: safemode: Wrote efuse to 5, read as fd. 9 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 8 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 7 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 6 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 5 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 4 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 3 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 2 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 1 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 0 attempts left
avrdude: and COULD NOT be changed
avrdude: safemode: Fuses not recovered, sorry

avrdude done.  Thank you.

As I'm unable to set the fuses it's no wonder that the actual upload doesn't work as well:
avrdude -b 19200 -c avrispv2 -p m328p -v -e -U flash:w:optiboot_atmega328.hex -U lock:w:0x0F:m -P /dev/ttyACM2

avrdude: Version 6.3
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2014 Joerg Wunsch

         System wide configuration file is "/etc/avrdude.conf"
         User configuration file is "/home/tabaluga/.avrduderc"
         User configuration file does not exist or is not a regular file, skipping

         Using Port                    : /dev/ttyACM2
         Using Programmer              : avrispv2
         Overriding Baud Rate          : 19200
         AVR Part                      : ATmega328P
         Chip Erase delay              : 9000 us
         PAGEL                         : PD7
         BS2                           : PC2
         RESET disposition             : dedicated
         RETRY pulse                   : SCK
         serial program mode           : yes
         parallel program mode         : yes
         Timeout                       : 200
         StabDelay                     : 100
         CmdexeDelay                   : 25
         SyncLoops                     : 32
         ByteDelay                     : 0
         PollIndex                     : 3
         PollValue                     : 0x53
         Memory Detail                 :

                                  Block Poll               Page                       Polled
           Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
           ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
           eeprom        65    20     4    0 no       1024    4      0  3600  3600 0xff 0xff
           flash         65     6   128    0 yes     32768  128    256  4500  4500 0xff 0xff
           lfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           hfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           efuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           lock           0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           calibration    0     0     0    0 no          1    0      0     0     0 0x00 0x00
           signature      0     0     0    0 no          3    0      0     0     0 0x00 0x00

         Programmer Type : STK500V2
         Description     : Atmel AVR ISP V2
         Programmer Model: STK500
         Hardware Version: 10
         Firmware Version Master : 2.10
avrdude: stk500v2_command(): command failed
avrdude: stk500v2_getparm(): failed to get parameter 0x9a
         Topcard         : Unknown
         Vtarget         : 3.3 V
         SCK period      : 17.4 us
         Varef           : 3.3 V
         Oscillator      : Off

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x1e950f (probably m328p)
avrdude: safemode: hfuse reads as D9
avrdude: safemode: efuse reads as FD
avrdude: erasing chip
avrdude: reading input file "optiboot_atmega328.hex"
avrdude: input file optiboot_atmega328.hex auto detected as Intel Hex
avrdude: writing flash (32768 bytes):

Writing | ################################################## | 100% 0.00s

avrdude: 32768 bytes of flash written
avrdude: verifying flash memory against optiboot_atmega328.hex:
avrdude: load data flash data from input file optiboot_atmega328.hex:
avrdude: input file optiboot_atmega328.hex auto detected as Intel Hex
avrdude: input file optiboot_atmega328.hex contains 32768 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 0.00s

avrdude: verifying ...
avrdude: 32768 bytes of flash verified
avrdude: reading input file "0x0F"
avrdude: writing lock (1 bytes):

Writing | ################################################## | 100% 0.01s

avrdude: 1 bytes of lock written
avrdude: verifying lock memory against 0x0F:
avrdude: load data lock data from input file 0x0F:
avrdude: input file 0x0F contains 1 bytes
avrdude: reading on-chip lock data:

Reading | ################################################## | 100% 0.00s

avrdude: verifying ...
avrdude: verification error, first mismatch at byte 0x0000
         0xcf != 0x0f
avrdude: verification error; content mismatch

avrdude: safemode: hfuse reads as D9
avrdude: safemode: efuse reads as FD
avrdude: safemode: Fuses OK (E:FD, H:D9, L:62)

avrdude done.  Thank you.

I personally doubt that the µC or my programmer are bricked because I'm able to upload program code via ISP as I always used to, also I've tried two different ATmega328p.
Do you see what I'm doing wrong?
Why does one actually have to change fuses before flashing the bootloader (just curious)?

user19409: I can see you are on Linux so I won't give you instructions for using AVR Studio - but do know that if you have access to a Windows machine that is another option you could try. 
I can't tell you exactly why it is not working through the Arduino IDE - it could be that the settings are not set correctly or any number of reasons. What I can say is that it is not seeing the AVRISPmkII. Try turning on verbose mode in the Arduino SE settings.
However when using avrdude, you are requesting the efuse be set to 0x05. The value of 0x05 (or b0000 0101) means that you are requesting a brownout detection of 2.7V. But because only the last 3 bits of the fuse are relevant, the chip fills the rest of the bits with 1 not 0. So b0000 0101 (aka 0x05) becomes b1111 1101 (aka 0xFD), hence you get a mismatch.
Also, according to my \Arduino-x.x.x\hardware\arduino\avr\boards.txt file, the fuses for the Arduino/Genduino Optiboot are:

low_fuses=0xFF
high_fuses=0xDE
extended_fuses=0xFD

Change your avrdude command to the following:
avrdude -b 19200 -c avrispv2 -p m328p -v -e -U efuse:w:0xFD:m -U hfuse:w:0xDE:m -U lfuse:w:0xFF:m -P /dev/ttyACM2

The last block of output in your question shows that you are trying to load the optiboot hex file. That part works so it seems, as it writes and verifies successfully. The interesting part is the lock bit fails verification. It is reading 0xCF which means it is in bootloader protection mode #3: LPM and SPM prohibited in boot loader section. 
From the datasheet:

SPM = Store Program Memory instruction
  LPM = Load  Program Memory instruction  

And

SPM is not allowed to write to the Boot Loader section, and LPM executing from the Application section is not allowed to read from the Boot Loader section. If Interrupt Vectors are placed in the Application section, interrupts are disabled while executing from the Boot Loader section.

But it appears that these lock bits can be removed by doing a chip erase:

The Boot Lock bits can be set in software and in Serial or Parallel Programming mode, but they can be cleared by a Chip Erase command only.

And

The Chip Erase will erase the Flash and EEPROM(1) memories plus Lock bits. The Lock bits are not reset until the program memory has been completely erased. The Fuse bits are not changed. A Chip Erase must be performed before the Flash and/or EEPROM are reprogrammed.

So it looks like you need to do a full chip erase with avrdude.

For reference I use the following fuse calculators:  

http://www.engbedded.com/fusecalc/ 
http://eleccelerator.com/fusecalc/fusecalc.php?chip=atmega328p 


38721: <p>I want to burn the arduino <code>optiboot_atmega328.hex</code> bootloader but it doesn't work. I remember that I was able to burn the BL using the arduino IDE which was quite easy, this time I'm having some problems.</p>

<p>I'm always using an avrispv2 programmer to flash my atmegas and it was also this programmer I used once to burn the BL. When I try, the IDE gives the following output:</p>

<pre><code>avrdude: Version 6.3-20171130
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2014 Joerg Wunsch

         System wide configuration file is "/home/xxx/Downloads/arduino-1.8.7-linux64/arduino-1.8.7/hardware/tools/avr/etc/avrdude.conf"
         User configuration file is "/home/xxx/.avrduderc"
         User configuration file does not exist or is not a regular file, skipping

         Using Port                    : /dev/ttyACM2
         Using Programmer              : stk500v1
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x00

avrdude done.  Thank you.

Fehler beim Brennen des Bootloaders.
</code></pre>

<p>After this didn't work I tried to manually upload the <code>optiboot_atmega328.hex</code> with avrdude on the commandline (<a href="https://learn.sparkfun.com/tutorials/installing-an-arduino-bootloader/all" rel="nofollow noreferrer">following this guide</a>). The output of avrdude is as follows:</p>

<pre><code>avrdude -b 19200 -c avrispv2 -p m328p -v -e -U efuse:w:0x05:m -U hfuse:w:0xD6:m -U lfuse:w:0xFF:m -P /dev/ttyACM2

avrdude: Version 6.3
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2014 Joerg Wunsch

         System wide configuration file is "/etc/avrdude.conf"
         User configuration file is "/home/tabaluga/.avrduderc"
         User configuration file does not exist or is not a regular file, skipping

         Using Port                    : /dev/ttyACM2
         Using Programmer              : avrispv2
         Overriding Baud Rate          : 19200
         AVR Part                      : ATmega328P
         Chip Erase delay              : 9000 us
         PAGEL                         : PD7
         BS2                           : PC2
         RESET disposition             : dedicated
         RETRY pulse                   : SCK
         serial program mode           : yes
         parallel program mode         : yes
         Timeout                       : 200
         StabDelay                     : 100
         CmdexeDelay                   : 25
         SyncLoops                     : 32
         ByteDelay                     : 0
         PollIndex                     : 3
         PollValue                     : 0x53
         Memory Detail                 :

                                  Block Poll               Page                       Polled
           Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
           ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
           eeprom        65    20     4    0 no       1024    4      0  3600  3600 0xff 0xff
           flash         65     6   128    0 yes     32768  128    256  4500  4500 0xff 0xff
           lfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           hfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           efuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           lock           0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           calibration    0     0     0    0 no          1    0      0     0     0 0x00 0x00
           signature      0     0     0    0 no          3    0      0     0     0 0x00 0x00

         Programmer Type : STK500V2
         Description     : Atmel AVR ISP V2
         Programmer Model: STK500
         Hardware Version: 10
         Firmware Version Master : 2.10
avrdude: stk500v2_command(): command failed
avrdude: stk500v2_getparm(): failed to get parameter 0x9a
         Topcard         : Unknown
         Vtarget         : 3.3 V
         SCK period      : 17.4 us
         Varef           : 3.3 V
         Oscillator      : Off

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x1e950f (probably m328p)
avrdude: safemode: hfuse reads as D9
avrdude: safemode: efuse reads as FD
avrdude: erasing chip
avrdude: reading input file "0x05"
avrdude: writing efuse (1 bytes):

Writing | ################################################## | 100% 0.01s

avrdude: 1 bytes of efuse written
avrdude: verifying efuse memory against 0x05:
avrdude: load data efuse data from input file 0x05:
avrdude: input file 0x05 contains 1 bytes
avrdude: reading on-chip efuse data:

Reading | ################################################## | 100% 0.00s

avrdude: verifying ...
avrdude: verification error, first mismatch at byte 0x0000
         0xfd != 0x05
avrdude: verification error; content mismatch

avrdude: safemode: hfuse reads as D9
avrdude: safemode: efuse reads as FD
avrdude: safemode: efuse changed! Was 5, and is now fd
Would you like this fuse to be changed back? [y/n] y
avrdude: safemode: Wrote efuse to 5, read as fd. 9 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 8 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 7 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 6 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 5 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 4 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 3 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 2 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 1 attempts left
avrdude: safemode: Wrote efuse to 5, read as fd. 0 attempts left
avrdude: and COULD NOT be changed
avrdude: safemode: Fuses not recovered, sorry

avrdude done.  Thank you.
</code></pre>

<p>As I'm unable to set the fuses it's no wonder that the actual upload doesn't work as well:</p>

<pre><code>avrdude -b 19200 -c avrispv2 -p m328p -v -e -U flash:w:optiboot_atmega328.hex -U lock:w:0x0F:m -P /dev/ttyACM2

avrdude: Version 6.3
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2014 Joerg Wunsch

         System wide configuration file is "/etc/avrdude.conf"
         User configuration file is "/home/tabaluga/.avrduderc"
         User configuration file does not exist or is not a regular file, skipping

         Using Port                    : /dev/ttyACM2
         Using Programmer              : avrispv2
         Overriding Baud Rate          : 19200
         AVR Part                      : ATmega328P
         Chip Erase delay              : 9000 us
         PAGEL                         : PD7
         BS2                           : PC2
         RESET disposition             : dedicated
         RETRY pulse                   : SCK
         serial program mode           : yes
         parallel program mode         : yes
         Timeout                       : 200
         StabDelay                     : 100
         CmdexeDelay                   : 25
         SyncLoops                     : 32
         ByteDelay                     : 0
         PollIndex                     : 3
         PollValue                     : 0x53
         Memory Detail                 :

                                  Block Poll               Page                       Polled
           Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
           ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
           eeprom        65    20     4    0 no       1024    4      0  3600  3600 0xff 0xff
           flash         65     6   128    0 yes     32768  128    256  4500  4500 0xff 0xff
           lfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           hfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           efuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           lock           0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           calibration    0     0     0    0 no          1    0      0     0     0 0x00 0x00
           signature      0     0     0    0 no          3    0      0     0     0 0x00 0x00

         Programmer Type : STK500V2
         Description     : Atmel AVR ISP V2
         Programmer Model: STK500
         Hardware Version: 10
         Firmware Version Master : 2.10
avrdude: stk500v2_command(): command failed
avrdude: stk500v2_getparm(): failed to get parameter 0x9a
         Topcard         : Unknown
         Vtarget         : 3.3 V
         SCK period      : 17.4 us
         Varef           : 3.3 V
         Oscillator      : Off

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x1e950f (probably m328p)
avrdude: safemode: hfuse reads as D9
avrdude: safemode: efuse reads as FD
avrdude: erasing chip
avrdude: reading input file "optiboot_atmega328.hex"
avrdude: input file optiboot_atmega328.hex auto detected as Intel Hex
avrdude: writing flash (32768 bytes):

Writing | ################################################## | 100% 0.00s

avrdude: 32768 bytes of flash written
avrdude: verifying flash memory against optiboot_atmega328.hex:
avrdude: load data flash data from input file optiboot_atmega328.hex:
avrdude: input file optiboot_atmega328.hex auto detected as Intel Hex
avrdude: input file optiboot_atmega328.hex contains 32768 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 0.00s

avrdude: verifying ...
avrdude: 32768 bytes of flash verified
avrdude: reading input file "0x0F"
avrdude: writing lock (1 bytes):

Writing | ################################################## | 100% 0.01s

avrdude: 1 bytes of lock written
avrdude: verifying lock memory against 0x0F:
avrdude: load data lock data from input file 0x0F:
avrdude: input file 0x0F contains 1 bytes
avrdude: reading on-chip lock data:

Reading | ################################################## | 100% 0.00s

avrdude: verifying ...
avrdude: verification error, first mismatch at byte 0x0000
         0xcf != 0x0f
avrdude: verification error; content mismatch

avrdude: safemode: hfuse reads as D9
avrdude: safemode: efuse reads as FD
avrdude: safemode: Fuses OK (E:FD, H:D9, L:62)

avrdude done.  Thank you.
</code></pre>

<p>I personally doubt that the µC or my programmer are bricked because I'm able to upload program code via ISP as I always used to, also I've tried two different ATmega328p.</p>

<p>Do you see what I'm doing wrong?
Why does one actually have to change fuses before flashing the bootloader (just curious)?</p>
 19409: <p>I can see you are on Linux so I won't give you instructions for using AVR Studio - but do know that if you have access to a Windows machine that is another option you could try. </p>

<p>I can't tell you exactly why it is not working through the Arduino IDE - it could be that the settings are not set correctly or any number of reasons. What I can say is that it is not seeing the AVRISPmkII. Try turning on verbose mode in the Arduino SE settings.</p>

<p>However when using avrdude, you are requesting the efuse be set to 0x05. The value of 0x05 (or b0000 0101) means that you are requesting a brownout detection of 2.7V. But because only the last 3 bits of the fuse are relevant, the chip fills the rest of the bits with 1 not 0. So b0000 0101 (aka 0x05) becomes b1111 1101 (aka 0xFD), hence you get a mismatch.</p>

<p>Also, according to my <code>\Arduino-x.x.x\hardware\arduino\avr\boards.txt</code> file, the fuses for the Arduino/Genduino Optiboot are:</p>

<ul>
<li>low_fuses=0xFF</li>
<li>high_fuses=0xDE</li>
<li>extended_fuses=0xFD</li>
</ul>

<p>Change your avrdude command to the following:</p>

<pre><code>avrdude -b 19200 -c avrispv2 -p m328p -v -e -U efuse:w:0xFD:m -U hfuse:w:0xDE:m -U lfuse:w:0xFF:m -P /dev/ttyACM2
</code></pre>

<p>The last block of output in your question shows that you are trying to load the optiboot hex file. That part works so it seems, as it writes and verifies successfully. The interesting part is the lock bit fails verification. It is reading 0xCF which means it is in bootloader protection mode #3: LPM and SPM prohibited in boot loader section. </p>

<p>From the datasheet:</p>

<blockquote>
  <p>SPM = Store Program Memory instruction<br>
  LPM = Load  Program Memory instruction  </p>
</blockquote>

<p>And</p>

<blockquote>
  <p>SPM is not allowed to write to the Boot Loader section, and LPM executing from the Application section is not allowed to read from the Boot Loader section. If Interrupt Vectors are placed in the Application section, interrupts are disabled while executing from the Boot Loader section.</p>
</blockquote>

<p>But it appears that these lock bits can be removed by doing a chip erase:</p>

<blockquote>
  <p>The Boot Lock bits can be set in software and in Serial or Parallel Programming mode, but they can be cleared by a Chip Erase command only.</p>
</blockquote>

<p>And</p>

<blockquote>
  <p>The Chip Erase will erase the Flash and EEPROM(1) memories plus Lock bits. The Lock bits are not reset until the program memory has been completely erased. The Fuse bits are not changed. A Chip Erase must be performed before the Flash and/or EEPROM are reprogrammed.</p>
</blockquote>

<p>So it looks like you need to do a full chip erase with avrdude.</p>

<hr>

<p>For reference I use the following fuse calculators:  </p>

<ul>
<li><a href="http://www.engbedded.com/fusecalc/" rel="nofollow noreferrer">http://www.engbedded.com/fusecalc/</a>  </li>
<li><a href="http://eleccelerator.com/fusecalc/fusecalc.php?chip=atmega328p" rel="nofollow noreferrer">http://eleccelerator.com/fusecalc/fusecalc.php?chip=atmega328p</a>  </li>
</ul>
