user13330: I have something strange going on with an output. When the following code is called the LED goes on, but it stays on, there is no blinking. If I comment out the set HIGH statement the LED never comes on (as expected). 
#define devicePin 10

void setup() {
  pinMode(devicePin, OUTPUT);
}

void loop() {
    digitalWrite(devicePin, HIGH);
    delay(2000);
    digitalWrite(devicePin, LOW);
}

Could I have damaged the board in some way?

user10794: Yes, the pin is going low. I tested it for you:

It went low for 6 µs, once every 2 seconds. :)

Overall, this is the effect:

As you can see, high for most of the time.

user13197: you forgot to add a delay after digitalWrite(devicePin, LOW);
#define devicePin 10

void setup() {
  pinMode(devicePin, OUTPUT);
}

void loop() {
    digitalWrite(devicePin, HIGH);
    delay(2000);
    digitalWrite(devicePin, LOW);
    delay(2000);
}


user-1: After you drive the pin low, you immediately go to the beginning of the loop and set the pin high (if you have an oscilloscope, you might see a very short downward pulse).
So, add another delay after digitalWrite(devicePin, LOW).  

13330: <p>I have something strange going on with an output. When the following code is called the LED goes on, but it stays on, there is no blinking. If I comment out the set HIGH statement the LED never comes on (as expected). </p>

<pre><code>#define devicePin 10

void setup() {
  pinMode(devicePin, OUTPUT);
}

void loop() {
    digitalWrite(devicePin, HIGH);
    delay(2000);
    digitalWrite(devicePin, LOW);
}
</code></pre>

<p>Could I have damaged the board in some way?</p>
 10794: <p>Yes, the pin is going low. I tested it for you:</p>

<p><a href="https://i.stack.imgur.com/qDZxx.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qDZxx.png" alt="Pin 10 going low"></a></p>

<p>It went low for 6 µs, once every 2 seconds. :)</p>

<hr>

<p>Overall, this is the effect:</p>

<p><a href="https://i.stack.imgur.com/3QuPS.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/3QuPS.png" alt="Pin 10 mainly high"></a></p>

<p>As you can see, high for most of the time.</p>
 13197: <p>you forgot to add a delay after digitalWrite(devicePin, LOW);</p>

<pre><code>#define devicePin 10

void setup() {
  pinMode(devicePin, OUTPUT);
}

void loop() {
    digitalWrite(devicePin, HIGH);
    delay(2000);
    digitalWrite(devicePin, LOW);
    delay(2000);
}
</code></pre>
 -1: <p>After you drive the pin low, you immediately go to the beginning of the loop and set the pin high (if you have an oscilloscope, you might see a very short downward pulse).<br>
So, add another delay after <code>digitalWrite(devicePin, LOW)</code>.  </p>
