Last piece of evidence.
I saw a small burn mark in the foam where the logic board rests. I traced that back to a spot on the board which is one of the raised component areas, and there are five on the logic board. Have no idea what they are. If you see the largest of these five, a square, the burned piece is the farthest one away from it, in the upper right-hand corner if looking away from the back where the ribbon cable and power supply are hooked up. Hope this makes sense.
In any case, there is a mark that I scraped off with a finger nail, and it was slightly charred.
I'm not sure this was all that happened to the logic board, but this one area, at least, suffered damage as a result of whatever took place.