Madcatz

first, as far as pressure goes, do you have to press on it for it to shutdown? you said you can just lay your finger on it now for it to go haywire, but are you literally just resting your finger on it not applying any pressure at all? if it is pressure related in that speicific area, few things come to mind. 1) touch pads are normally held in place with screws, its possible one of them is loose or is longer that what should be there and touching something to ground it out. 2) you said its over the disc drive, take the drive out and see if the same thing happens.

also if you plan on tearing it apart again, this time look at the cables and wires, see if they look worn or lying against some solder connections that might be puncturing the wire.