I received a PC Engine and a Core Grafx 2 that were described as not working (not powering on). The PC Engine was an easy fix as it was just a blown fuse. The Core Grafx powered on but gave a white screen, I cleaned the console thoroughly and tried again but with the same result.
There was some dust/stuff? in the Hucard slot so for this reason I suspected the issue could be with the card slot, and I was right. I went through the painstaking process of transplanting the working card slot board over from the PC Engine and now the Core Grafx is working. I then put the faulty card slot board from the Core Grafx to the PC Engine and it is giving a pale blue screen.
The pins in the slot look fine and I cleaned it with some alcohol, but it made no difference.