He used clear acrylic on the uncovered grounds and traces. +1 on the nice work. I wouldn't have been excited about replacing a ton of components to repair a board, but you've got me inspired. I may get out a toasty old gameplan MPU and see if I can get it working again. I've got a working game to test it in.
I get really frustrated when I do a bunch of board work, test the work with the mm to confirm all the associated traces are good, plug it in and something doesn t work or it didn't fix the problem. or something else breaks.
I redid the 40 pin connector on my solar fire, and as soon as I plugged it in the issues I had hoped would be fixed were all completely unchanged. and a flipper stopped working again after testing. I just had to set it aside and work on other stuff for a while.