Yes was working prior although it was away for a month with a guy to solder the key writing wires (yes it took that long for 4 wires) but he's a professional and sure he looked after itBlack screen is caused by an issue with encryption keys. The program code is being read but it can’t boot
I’m not sure if you said you got past that part or you’re currently running decrypted games, but that issue was probably related to power - the resistor is just there to help smooth out a clock pin. I’ve often had issues with the older revision boards and trying to load encryption keys, they seem to be more sensitive to less than 5.0v/12.0v
The graphics issue is an interconnect issue either between the multi and the B board or A and B boards
Was this a working set prior to the multi installation or did you buy it dead?
Check for bent pins between A and B boards, if possible try the A with another B and/or B on another A to see if you can narrow it
It seems to be pushed all the way in on all boards its hard to tell with the small double pins in the middle but I tested with my multi meter and was ok