The best place to start is find out what revision motherboard the person has. As battery damage is the most common cause of boot errors. @vectrex If you haven't noticed i run a web page and discord that focus on the PGM hardware. I have LOTS of info on the site (Including repair info).
Everything is in my Signature below or go here https://igspgm.com/
My most viewed video is my PGM Motherboard Buying Guide. Watching that will help you find out which revision motherboard you have.
I had an issue with a stuck button caused by the U5 chip.
There were signs of oxidation on the chip itself, as well as on the pads and PCB traces.
Rather than spending time troubleshooting further, I rebuilt the damaged traces and pads and replaced the ASIC with one salvaged from a donor motherboard.
After the repair, the stuck button issue was completely resolved.
I picked up a faulty
Mother board and
Demon front pcb
I will take pics of my mother board and check the u5 chip asap..
Screen I get from the demon cart in my
Good working pgm is lots of repeated same static character