To be expected ! This board will be a REAL challenge.

The jumpers must be correct for the ROMs you are using - if the jumpers are wrong, the board won't boot.

Eliminate the Reset section by shorting out pins 39 & 40 on the CPU.

My guess would be a short in the Address or Data lines. The U11 PIA would be where I would start. I have printout the schematic on an A3 page and work through all the permutations and combinations of the Address and Data lines.