Today I repaired a PS4 with the blue light of death. I removed the NOR chip,dumped,patched and wrote it so I could watch the UART and see what was causing the issue.

It showed the error of DCT 01 and 02 disabled. Which pinpoints one or two RAM modules are not communicating with the APU.

I went ahead and reballed the APU and fixed the issue. This is very common with the OG models 1002A and 1102A units.

After the reball the console was back up and running like new