No power nor red light. PSU has the right voltage and fuse works.

I purchased a PS2 fat 30002 with GH-006 MB. It was working, had to take apart as it was horrendously dirty and a fire hazard. After cleaning the console, it did not power on. There is no red light displaying at the power button either. Trying to find any schematics on this board is near impossible. The SDM fuses I could find was working on the main board as well as the controller board. The power board was displaying the right voltage as well when plugged in and the fuse was fine. What could be the problem??