user52441: seems i damaged one of my Nanos. i have to say i am new to Arduino and have basic electronik skills and i realized after shopping via amazon that the Nanos i have are clones with CH340G.
never the less they are working. i was building a light driven open/close circuit for my chickens. using L293D motordriver, LCD, photocell. my sketch was just reading the photocell and outputting it on the LCD. not yet using the L293D in the sketch but assembled it already (without Motors and MV+).
The program was running for ~ 2 minutes. i was testing the reading for the photocell and was wondering why at low light the reading was still quite high ~ 600+. then all disappeared from the LCD apart of the background light.
as i couldnt get it running i tried to upload Blink again -> not working
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x96 code here
...
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x96
Problem beim Hochladen auf das Board. Hilfestellung dazu unter http://www.arduino.cc/en/Guide/Troubleshooting#upload.

after a while i was reading about programmers so i turned another Nano into a ArduinoISP trying to write either Booloader or Sketch via ISP bypassing USB (as i understood the different articles)
which gave
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x15
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x15

avrdude: stk500_getparm(): (a) protocol error, expect=0x14, resp=0x14

avrdude: stk500_getparm(): (a) protocol error, expect=0x14, resp=0x01
avrdude: stk500_initialize(): (a) protocol error, expect=0x14, resp=0x10
avrdude: initialization failed, rc=-1
     Double check connections and try again, or use -F to override
     this check.

avrdude: stk500_disable(): unknown response=0x12
Der ausgewählte serielle Port avrdude: stk500_disable(): unknown response=0x12
 ist nicht vorhanden oder das Board ist nicht angeschlossen

then i used Atmega_Board_Detector and Atmega_Board_Programmer which both seem to work. 
output of Boarddetector:
    Atmega chip detector.
    Written by Nick Gammon.
    Version 1.20
    Compiled on Dec 27 2018 at 15:13:27 with Arduino IDE 10808.
    Attempting to enter ICSP programming mode ...
    Entered programming mode OK.
    Signature = 0x1E 0x95 0x0F 
    Processor = ATmega328P
    Flash memory size = 32768 bytes.
    LFuse = 0xFF 
    HFuse = 0xDE 
    EFuse = 0xFD 
    Lock byte = 0xEF 
    Clock calibration = 0x9E 
    Bootloader in use: Yes
    EEPROM preserved through erase: No
    Watchdog timer always on: No
    Bootloader is 512 bytes starting at 7E00

    Bootloader:

    7E00: 0x11 0x24 0x84 0xB7 0x14 0xBE 0x81 0xFF 0xF0 0xD0 0x85 0xE0 0x80 0x93 0x81 0x00 
    7E10: 0x82 0xE0 0x80 0x93 0xC0 0x00 0x88 0xE1 0x80 0x93 0xC1 0x00 0x86 0xE0 0x80 0x93 
    7E20: 0xC2 0x00 0x80 0xE1 0x80 0x93 0xC4 0x00 0x8E 0xE0 0xC9 0xD0 0x25 0x9A 0x86 0xE0 
    7E30: 0x20 0xE3 0x3C 0xEF 0x91 0xE0 0x30 0x93 0x85 0x00 0x20 0x93 0x84 0x00 0x96 0xBB 
    7E40: 0xB0 0x9B 0xFE 0xCF 0x1D 0x9A 0xA8 0x95 0x81 0x50 0xA9 0xF7 0xCC 0x24 0xDD 0x24 
    7E50: 0x88 0x24 0x83 0x94 0xB5 0xE0 0xAB 0x2E 0xA1 0xE1 0x9A 0x2E 0xF3 0xE0 0xBF 0x2E 
    7E60: 0xA2 0xD0 0x81 0x34 0x61 0xF4 0x9F 0xD0 0x08 0x2F 0xAF 0xD0 0x02 0x38 0x11 0xF0 
    7E70: 0x01 0x38 0x11 0xF4 0x84 0xE0 0x01 0xC0 0x83 0xE0 0x8D 0xD0 0x89 0xC0 0x82 0x34 
    7E80: 0x11 0xF4 0x84 0xE1 0x03 0xC0 0x85 0x34 0x19 0xF4 0x85 0xE0 0xA6 0xD0 0x80 0xC0 
    7E90: 0x85 0x35 0x79 0xF4 0x88 0xD0 0xE8 0x2E 0xFF 0x24 0x85 0xD0 0x08 0x2F 0x10 0xE0 
    7EA0: 0x10 0x2F 0x00 0x27 0x0E 0x29 0x1F 0x29 0x00 0x0F 0x11 0x1F 0x8E 0xD0 0x68 0x01 
    7EB0: 0x6F 0xC0 0x86 0x35 0x21 0xF4 0x84 0xE0 0x90 0xD0 0x80 0xE0 0xDE 0xCF 0x84 0x36 
    7EC0: 0x09 0xF0 0x40 0xC0 0x70 0xD0 0x6F 0xD0 0x08 0x2F 0x6D 0xD0 0x80 0xE0 0xC8 0x16 
    7ED0: 0x80 0xE7 0xD8 0x06 0x18 0xF4 0xF6 0x01 0xB7 0xBE 0xE8 0x95 0xC0 0xE0 0xD1 0xE0 
    7EE0: 0x62 0xD0 0x89 0x93 0x0C 0x17 0xE1 0xF7 0xF0 0xE0 0xCF 0x16 0xF0 0xE7 0xDF 0x06 
    7EF0: 0x18 0xF0 0xF6 0x01 0xB7 0xBE 0xE8 0x95 0x68 0xD0 0x07 0xB6 0x00 0xFC 0xFD 0xCF 
    7F00: 0xA6 0x01 0xA0 0xE0 0xB1 0xE0 0x2C 0x91 0x30 0xE0 0x11 0x96 0x8C 0x91 0x11 0x97 
    7F10: 0x90 0xE0 0x98 0x2F 0x88 0x27 0x82 0x2B 0x93 0x2B 0x12 0x96 0xFA 0x01 0x0C 0x01 
    7F20: 0x87 0xBE 0xE8 0x95 0x11 0x24 0x4E 0x5F 0x5F 0x4F 0xF1 0xE0 0xA0 0x38 0xBF 0x07 
    7F30: 0x51 0xF7 0xF6 0x01 0xA7 0xBE 0xE8 0x95 0x07 0xB6 0x00 0xFC 0xFD 0xCF 0x97 0xBE 
    7F40: 0xE8 0x95 0x26 0xC0 0x84 0x37 0xB1 0xF4 0x2E 0xD0 0x2D 0xD0 0xF8 0x2E 0x2B 0xD0 
    7F50: 0x3C 0xD0 0xF6 0x01 0xEF 0x2C 0x8F 0x01 0x0F 0x5F 0x1F 0x4F 0x84 0x91 0x1B 0xD0 
    7F60: 0xEA 0x94 0xF8 0x01 0xC1 0xF7 0x08 0x94 0xC1 0x1C 0xD1 0x1C 0xFA 0x94 0xCF 0x0C 
    7F70: 0xD1 0x1C 0x0E 0xC0 0x85 0x37 0x39 0xF4 0x28 0xD0 0x8E 0xE1 0x0C 0xD0 0x85 0xE9 
    7F80: 0x0A 0xD0 0x8F 0xE0 0x7A 0xCF 0x81 0x35 0x11 0xF4 0x88 0xE0 0x18 0xD0 0x1D 0xD0 
    7F90: 0x80 0xE1 0x01 0xD0 0x65 0xCF 0x98 0x2F 0x80 0x91 0xC0 0x00 0x85 0xFF 0xFC 0xCF 
    7FA0: 0x90 0x93 0xC6 0x00 0x08 0x95 0x80 0x91 0xC0 0x00 0x87 0xFF 0xFC 0xCF 0x80 0x91 
    7FB0: 0xC0 0x00 0x84 0xFD 0x01 0xC0 0xA8 0x95 0x80 0x91 0xC6 0x00 0x08 0x95 0xE0 0xE6 
    7FC0: 0xF0 0xE0 0x98 0xE1 0x90 0x83 0x80 0x83 0x08 0x95 0xED 0xDF 0x80 0x32 0x19 0xF0 
    7FD0: 0x88 0xE0 0xF5 0xDF 0xFF 0xCF 0x84 0xE1 0xDE 0xCF 0x1F 0x93 0x18 0x2F 0xE3 0xDF 
    7FE0: 0x11 0x50 0xE9 0xF7 0xF2 0xDF 0x1F 0x91 0x08 0x95 0x80 0xE0 0xE8 0xDF 0xEE 0x27 
    7FF0: 0xFF 0x27 0x09 0x94 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0x04 0x04 

    MD5 sum of bootloader = 0xFB 0xF4 0x9B 0x7B 0x59 0x73 0x7F 0x65 0xE8 0xD0 0xF8 0xA5 0x08 0x12 0xE7 0x9F 
    Bootloader name: optiboot_atmega328

    First 256 bytes of program memory:

    00: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    10: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    20: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    30: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    40: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    50: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    60: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    70: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    80: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    90: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    A0: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    B0: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    C0: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    D0: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    E0: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    F0: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 

    Programming mode off.

Output of Board Programmer:
    Atmega chip programmer.
    Written by Nick Gammon.
    Version 1.38
    Compiled on Dec 27 2018 at 15:15:38 with Arduino IDE 10808.
    Attempting to enter ICSP programming mode ...
    Entered programming mode OK.
    Signature = 0x1E 0x95 0x0F 
    Processor = ATmega328P
    Flash memory size = 32768 bytes.
    LFuse = 0xFF 
    HFuse = 0xDE 
    EFuse = 0xFD 
    Lock byte = 0xEF 
    Clock calibration = 0x9E 
    Type 'L' to use Lilypad (8 MHz) loader, or 'U' for Uno (16 MHz) loader ...
    Using Uno Optiboot 16 MHz loader.
    Bootloader address = 0x7E00
    Bootloader length = 512 bytes.
    Type 'Q' to quit, 'V' to verify, or 'G' to program the chip with the bootloader ...
    Erasing chip ...
    Writing bootloader ...
    Committing page starting at 0x7E00
    Committing page starting at 0x7E80
    Committing page starting at 0x7F00
    Committing page starting at 0x7F80
    Written.
    Verifying ...
    No errors found.
    Writing fuses ...
    LFuse = 0xFF 
    HFuse = 0xDE 
    EFuse = 0xFD 
    Lock byte = 0xEF 
    Clock calibration = 0x9E 
    Done.
    Programming mode off.
    Type 'C' when ready to continue with another chip ...

other observations:
when trying to upload a sketch the rx LED blinks where thin a few times but not bright and at the speed it usually does. the L LED blinks at power on a few times.
i have 2 questions:

can you see anything in my circuit that could have damaged the NANO?
any idea to recover the NANO?

i am more curious on the first question as i don't want to take out another one. the second is more curiosity what can be done on a Nano.
and i am clueless why it died as i run all the experiments individually on an UNO
attached pictures and my fight with Fritzing for the schematics.




Many Thanks already
UPDATE:
just recognized that also my working NANOs can not be programmed via ArduinoISP Sketch using a Programmer NANO. so as the tools from Nick Gammon.
are working https://github.com/nickgammon/arduino_sketches. i assume my chip is working and it is up to the USB Chip or connection.
UPDATE2:
my NANO is fully back in live. what ever happened seems to have corrupted my flash. so after the TIPs from @Majenko with the 10uF Cap between Reset and GND i was able to programm via a "Programmernano". but here is another catch
when you first flash bootloader and then right away flash a sketch via programmer as well, this erases again the bootloader. you can check this with the 
Atmega chip detector.
Written by Nick Gammon.
    Bootloader is 2048 bytes starting at 7800

    Bootloader:

    7800: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    7810: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    7820: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    7830: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 

So i just flash the Bootloader via ArduinoISP and then connect the NANO directly to USB to flash a sketch

user50339: Try replacing the diode as in this link, it worked for me: https://forum.arduino.cc/index.php?topic=166089.0
A short on VCC might damage the diode.
As for the answer to the first question, yes there is a flaw in the design, if the external power is lost the LCD and the L293D will be powered from USB through the above diode.
"Small change" , see Juraj's comment below. 

user10794: Based on the output from my sketches that you have posted, the CPU chip is fine (Atmega328P). Since you cannot program via the USB port is looks likely that the CH340G is damaged.
A fall-back position is to use another one of the sketches (Atmega_Hex_Uploader) in the link you posted, and upload code via the SPI interface. To make this work you need to purchase a micro-SD card interface as described here for around $US 15.
As for why it failed, this should be investigated promptly. Possibly the answer by Dorian will help.

52441: <p>seems i damaged one of my Nanos. i have to say i am new to Arduino and have basic electronik skills and i realized after shopping via amazon that the Nanos i have are clones with CH340G.
never the less they are working. i was building a light driven open/close circuit for my chickens. using L293D motordriver, LCD, photocell. my sketch was just reading the photocell and outputting it on the LCD. not yet using the L293D in the sketch but assembled it already (without Motors and MV+).
The program was running for ~ 2 minutes. i was testing the reading for the photocell and was wondering why at low light the reading was still quite high ~ 600+. then all disappeared from the LCD apart of the background light.
as i couldnt get it running i tried to upload Blink again -> not working</p>

<pre><code>avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x96 code here
...
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x96
Problem beim Hochladen auf das Board. Hilfestellung dazu unter http://www.arduino.cc/en/Guide/Troubleshooting#upload.
</code></pre>

<p>after a while i was reading about programmers so i turned another Nano into a ArduinoISP trying to write either Booloader or Sketch via ISP bypassing USB (as i understood the different articles)
which gave</p>

<pre><code>avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x15
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x15

avrdude: stk500_getparm(): (a) protocol error, expect=0x14, resp=0x14

avrdude: stk500_getparm(): (a) protocol error, expect=0x14, resp=0x01
avrdude: stk500_initialize(): (a) protocol error, expect=0x14, resp=0x10
avrdude: initialization failed, rc=-1
     Double check connections and try again, or use -F to override
     this check.

avrdude: stk500_disable(): unknown response=0x12
Der ausgewählte serielle Port avrdude: stk500_disable(): unknown response=0x12
 ist nicht vorhanden oder das Board ist nicht angeschlossen
</code></pre>

<p>then i used Atmega_Board_Detector and Atmega_Board_Programmer which both seem to work. 
output of Boarddetector:</p>

<pre><code>    Atmega chip detector.
    Written by Nick Gammon.
    Version 1.20
    Compiled on Dec 27 2018 at 15:13:27 with Arduino IDE 10808.
    Attempting to enter ICSP programming mode ...
    Entered programming mode OK.
    Signature = 0x1E 0x95 0x0F 
    Processor = ATmega328P
    Flash memory size = 32768 bytes.
    LFuse = 0xFF 
    HFuse = 0xDE 
    EFuse = 0xFD 
    Lock byte = 0xEF 
    Clock calibration = 0x9E 
    Bootloader in use: Yes
    EEPROM preserved through erase: No
    Watchdog timer always on: No
    Bootloader is 512 bytes starting at 7E00

    Bootloader:

    7E00: 0x11 0x24 0x84 0xB7 0x14 0xBE 0x81 0xFF 0xF0 0xD0 0x85 0xE0 0x80 0x93 0x81 0x00 
    7E10: 0x82 0xE0 0x80 0x93 0xC0 0x00 0x88 0xE1 0x80 0x93 0xC1 0x00 0x86 0xE0 0x80 0x93 
    7E20: 0xC2 0x00 0x80 0xE1 0x80 0x93 0xC4 0x00 0x8E 0xE0 0xC9 0xD0 0x25 0x9A 0x86 0xE0 
    7E30: 0x20 0xE3 0x3C 0xEF 0x91 0xE0 0x30 0x93 0x85 0x00 0x20 0x93 0x84 0x00 0x96 0xBB 
    7E40: 0xB0 0x9B 0xFE 0xCF 0x1D 0x9A 0xA8 0x95 0x81 0x50 0xA9 0xF7 0xCC 0x24 0xDD 0x24 
    7E50: 0x88 0x24 0x83 0x94 0xB5 0xE0 0xAB 0x2E 0xA1 0xE1 0x9A 0x2E 0xF3 0xE0 0xBF 0x2E 
    7E60: 0xA2 0xD0 0x81 0x34 0x61 0xF4 0x9F 0xD0 0x08 0x2F 0xAF 0xD0 0x02 0x38 0x11 0xF0 
    7E70: 0x01 0x38 0x11 0xF4 0x84 0xE0 0x01 0xC0 0x83 0xE0 0x8D 0xD0 0x89 0xC0 0x82 0x34 
    7E80: 0x11 0xF4 0x84 0xE1 0x03 0xC0 0x85 0x34 0x19 0xF4 0x85 0xE0 0xA6 0xD0 0x80 0xC0 
    7E90: 0x85 0x35 0x79 0xF4 0x88 0xD0 0xE8 0x2E 0xFF 0x24 0x85 0xD0 0x08 0x2F 0x10 0xE0 
    7EA0: 0x10 0x2F 0x00 0x27 0x0E 0x29 0x1F 0x29 0x00 0x0F 0x11 0x1F 0x8E 0xD0 0x68 0x01 
    7EB0: 0x6F 0xC0 0x86 0x35 0x21 0xF4 0x84 0xE0 0x90 0xD0 0x80 0xE0 0xDE 0xCF 0x84 0x36 
    7EC0: 0x09 0xF0 0x40 0xC0 0x70 0xD0 0x6F 0xD0 0x08 0x2F 0x6D 0xD0 0x80 0xE0 0xC8 0x16 
    7ED0: 0x80 0xE7 0xD8 0x06 0x18 0xF4 0xF6 0x01 0xB7 0xBE 0xE8 0x95 0xC0 0xE0 0xD1 0xE0 
    7EE0: 0x62 0xD0 0x89 0x93 0x0C 0x17 0xE1 0xF7 0xF0 0xE0 0xCF 0x16 0xF0 0xE7 0xDF 0x06 
    7EF0: 0x18 0xF0 0xF6 0x01 0xB7 0xBE 0xE8 0x95 0x68 0xD0 0x07 0xB6 0x00 0xFC 0xFD 0xCF 
    7F00: 0xA6 0x01 0xA0 0xE0 0xB1 0xE0 0x2C 0x91 0x30 0xE0 0x11 0x96 0x8C 0x91 0x11 0x97 
    7F10: 0x90 0xE0 0x98 0x2F 0x88 0x27 0x82 0x2B 0x93 0x2B 0x12 0x96 0xFA 0x01 0x0C 0x01 
    7F20: 0x87 0xBE 0xE8 0x95 0x11 0x24 0x4E 0x5F 0x5F 0x4F 0xF1 0xE0 0xA0 0x38 0xBF 0x07 
    7F30: 0x51 0xF7 0xF6 0x01 0xA7 0xBE 0xE8 0x95 0x07 0xB6 0x00 0xFC 0xFD 0xCF 0x97 0xBE 
    7F40: 0xE8 0x95 0x26 0xC0 0x84 0x37 0xB1 0xF4 0x2E 0xD0 0x2D 0xD0 0xF8 0x2E 0x2B 0xD0 
    7F50: 0x3C 0xD0 0xF6 0x01 0xEF 0x2C 0x8F 0x01 0x0F 0x5F 0x1F 0x4F 0x84 0x91 0x1B 0xD0 
    7F60: 0xEA 0x94 0xF8 0x01 0xC1 0xF7 0x08 0x94 0xC1 0x1C 0xD1 0x1C 0xFA 0x94 0xCF 0x0C 
    7F70: 0xD1 0x1C 0x0E 0xC0 0x85 0x37 0x39 0xF4 0x28 0xD0 0x8E 0xE1 0x0C 0xD0 0x85 0xE9 
    7F80: 0x0A 0xD0 0x8F 0xE0 0x7A 0xCF 0x81 0x35 0x11 0xF4 0x88 0xE0 0x18 0xD0 0x1D 0xD0 
    7F90: 0x80 0xE1 0x01 0xD0 0x65 0xCF 0x98 0x2F 0x80 0x91 0xC0 0x00 0x85 0xFF 0xFC 0xCF 
    7FA0: 0x90 0x93 0xC6 0x00 0x08 0x95 0x80 0x91 0xC0 0x00 0x87 0xFF 0xFC 0xCF 0x80 0x91 
    7FB0: 0xC0 0x00 0x84 0xFD 0x01 0xC0 0xA8 0x95 0x80 0x91 0xC6 0x00 0x08 0x95 0xE0 0xE6 
    7FC0: 0xF0 0xE0 0x98 0xE1 0x90 0x83 0x80 0x83 0x08 0x95 0xED 0xDF 0x80 0x32 0x19 0xF0 
    7FD0: 0x88 0xE0 0xF5 0xDF 0xFF 0xCF 0x84 0xE1 0xDE 0xCF 0x1F 0x93 0x18 0x2F 0xE3 0xDF 
    7FE0: 0x11 0x50 0xE9 0xF7 0xF2 0xDF 0x1F 0x91 0x08 0x95 0x80 0xE0 0xE8 0xDF 0xEE 0x27 
    7FF0: 0xFF 0x27 0x09 0x94 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0x04 0x04 

    MD5 sum of bootloader = 0xFB 0xF4 0x9B 0x7B 0x59 0x73 0x7F 0x65 0xE8 0xD0 0xF8 0xA5 0x08 0x12 0xE7 0x9F 
    Bootloader name: optiboot_atmega328

    First 256 bytes of program memory:

    00: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    10: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    20: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    30: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    40: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    50: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    60: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    70: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    80: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    90: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    A0: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    B0: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    C0: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    D0: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    E0: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    F0: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 

    Programming mode off.
</code></pre>

<p>Output of Board Programmer:</p>

<pre><code>    Atmega chip programmer.
    Written by Nick Gammon.
    Version 1.38
    Compiled on Dec 27 2018 at 15:15:38 with Arduino IDE 10808.
    Attempting to enter ICSP programming mode ...
    Entered programming mode OK.
    Signature = 0x1E 0x95 0x0F 
    Processor = ATmega328P
    Flash memory size = 32768 bytes.
    LFuse = 0xFF 
    HFuse = 0xDE 
    EFuse = 0xFD 
    Lock byte = 0xEF 
    Clock calibration = 0x9E 
    Type 'L' to use Lilypad (8 MHz) loader, or 'U' for Uno (16 MHz) loader ...
    Using Uno Optiboot 16 MHz loader.
    Bootloader address = 0x7E00
    Bootloader length = 512 bytes.
    Type 'Q' to quit, 'V' to verify, or 'G' to program the chip with the bootloader ...
    Erasing chip ...
    Writing bootloader ...
    Committing page starting at 0x7E00
    Committing page starting at 0x7E80
    Committing page starting at 0x7F00
    Committing page starting at 0x7F80
    Written.
    Verifying ...
    No errors found.
    Writing fuses ...
    LFuse = 0xFF 
    HFuse = 0xDE 
    EFuse = 0xFD 
    Lock byte = 0xEF 
    Clock calibration = 0x9E 
    Done.
    Programming mode off.
    Type 'C' when ready to continue with another chip ...
</code></pre>

<p>other observations:
when trying to upload a sketch the rx LED blinks where thin a few times but not bright and at the speed it usually does. the L LED blinks at power on a few times.</p>

<p>i have 2 questions:</p>

<ol>
<li><p>can you see anything in my circuit that could have damaged the NANO?</p></li>
<li><p>any idea to recover the NANO?</p></li>
</ol>

<p>i am more curious on the first question as i don't want to take out another one. the second is more curiosity what can be done on a Nano.
and i am clueless why it died as i run all the experiments individually on an UNO</p>

<p>attached pictures and my fight with Fritzing for the schematics.
<a href="https://i.stack.imgur.com/aNv8K.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/aNv8K.jpg" alt="enter image description here"></a>
<a href="https://i.stack.imgur.com/LrWQY.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LrWQY.jpg" alt="enter image description here"></a>
<a href="https://i.stack.imgur.com/1R3Xu.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1R3Xu.jpg" alt="enter image description here"></a>
<a href="https://i.stack.imgur.com/hJgt1.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/hJgt1.jpg" alt="enter image description here"></a>
Many Thanks already</p>

<p>UPDATE:
just recognized that also my working NANOs can not be programmed via ArduinoISP Sketch using a Programmer NANO. so as the tools from Nick Gammon.
are working <a href="https://github.com/nickgammon/arduino_sketches" rel="nofollow noreferrer">https://github.com/nickgammon/arduino_sketches</a>. i assume my chip is working and it is up to the USB Chip or connection.</p>

<p>UPDATE2:
my NANO is fully back in live. what ever happened seems to have corrupted my flash. so after the TIPs from @Majenko with the 10uF Cap between Reset and GND i was able to programm via a "Programmernano". but here is another catch
when you first flash bootloader and then right away flash a sketch via programmer as well, this erases again the bootloader. you can check this with the 
Atmega chip detector.
Written by Nick Gammon.</p>

<pre><code>    Bootloader is 2048 bytes starting at 7800

    Bootloader:

    7800: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    7810: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    7820: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
    7830: 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 
</code></pre>

<p>So i just flash the Bootloader via ArduinoISP and then connect the NANO directly to USB to flash a sketch</p>
 50339: <p>Try replacing the diode as in this link, it worked for me: <a href="https://forum.arduino.cc/index.php?topic=166089.0" rel="nofollow noreferrer">https://forum.arduino.cc/index.php?topic=166089.0</a></p>

<p>A short on VCC might damage the diode.</p>

<p>As for the answer to the first question, yes there is a flaw in the design, if the external power is lost the LCD and the L293D will be powered from USB through the above diode.</p>

<p>"Small change" , see Juraj's comment below. </p>
 10794: <p>Based on the output from my sketches that you have posted, the CPU chip is fine (Atmega328P). Since you cannot program via the USB port is looks likely that the CH340G is damaged.</p>

<p>A fall-back position is to use another one of the sketches (Atmega_Hex_Uploader) in the link you posted, and upload code via the SPI interface. To make this work you need to purchase a micro-SD card interface as described <a href="http://www.gammon.com.au/forum/?id=11638" rel="nofollow noreferrer">here</a> for around $US 15.</p>

<p>As for why it failed, this should be investigated promptly. Possibly <a href="https://arduino.stackexchange.com/a/60064/10794">the answer by Dorian</a> will help.</p>
