Well, for better or worse I have progress... When I came back into the room, the BIOS was frozen. After force restarting the computer, it didn't make POST, and upon further investigation the MB is reading code 00.
Now, It doesn't make sense that these issues could even be related... Maybe all the hard resets cooked something important because something somewhere is well and truly fried. In any case, this is a problem for tomorrow's me. I'll probably start by pulling off the clc, and if that doesn't end any insights, I'll try buying a new PSU.
EDIT: Could I have somehow killed the BIOS? Would that cause a post code 00?