Well... I made a miscalculation. 
I used adhesives to "mount" hard drives to the sloped ceiling of my room. Low stakes, I just didn't want to put more effort in, and wouldn't need these back. ADHD said "MAKE IT WORK!" 
Well, now I wanted it back. I think demounting it destroyed it. That board flexed frighteningly far, and now the insulating layer under it is sticking out from underneath.

Ah well, lesson learned. I'll unscrew this board and reposition that layer before I attempt to fire it up.