Thanks, as I mentioned in my initial post, there is indeed nothing displayed on the front LCD, it just switches on and lights up. For the testing I mentioned, I had a PS2 connected via AV2 (YPbPr Component). I used that because I’m still waiting on a replacement SCART socket to arrive from overseas. Electrically, it should be the same as having it installed with nothing plugged into AV1, shouldn’t it? In any case, I did try cycling with the PCB button, but didn’t get any response.
I’ll go over a few more times, of course, but I’m doubtful at this point that a solder join is the issue.