Providing you are getting +12V from the power supply on the yellow/black wires and +5V from the red/black wires (or thereabouts it does not have to be dead on accurate) then you are most likely still having a failure to read the PROM.

I've created a document that traces out every pin from the PROM to the nearest top solder point to help people ensure that they have continuity if that helps:

https://drive.google.com/open?id=1kU...MPktXyHxoHZsrU

I've got a 400dpi version if you really need it but it is a BIG file.