Moving Lights Roasting on Burning Circuit Boards...

So I tried to be a little creative with the thread title given the Christmas holiday, but the fact is true - one of my Tempest 250s decided to fry yesterday. Nothing too terribly exciting happened - went to power on the fixture, the fixture buzzed as normal when striking the lamp, except the lamp didn't pop on and a fair amount of smoke started spewing out the cooling fans. I of course unplugged the unit immediately (less than 5 seconds after plugging it in, so this happened very quickly), and ran the 50 pound beast outside to avoid setting off the fire alarm.

So after opening the unit up it's very obvious where the 'fire' took place. It looks like excessive voltage or current came in through the screw terminal connecting this board to the lamp ignitor. Pictures are linked below. This is the only part that seems to have been damaged (ignitor, ballast, transformer LOOK to be okay). I've repaired circuit boards at the component level before and of course will try on this one as well, but my bigger question is what happened?!? The unit ran just fine the day before and was not moved between the two days, so no chance of jostling something loose. I have two other identical units and am now afraid the same thing is going to happen to them! Any input would be much appreciated!