Completely removed the board from the case, plugged in the original ROM's, SCSI chip, reseated the DRAM's (iffy stuff) checked all jumpers, pressed down all the big chip's a bit, prayed for half an hour the God of Technology and switched on the power to watch to a black screen.
Moral of the story, the God of Technologoy does not care about us Amigans and Amiga's.