Precision 5550 No boot, but LCD BIST works

My 5550 Will not boot. the keyboard lights up for 1 second, then goes black. Few seconds later it does the same thing. Cycle goes on forever. This only happens with the charger plugged in. It shows no sign of life with just the battery. Probing the motherboards main power rail shows no short circuit. coils and mosfets read 0.6-0.9ohms to ground. The power state in this bootloop is s0, seen by probing the fan pin as well as the keyboard pin for pp5 s0. This tells me all previous power states pass, correct? Something on s0 fails? I have the schematics for this motherboard if someone could guide me further in troubleshooting this motherboard, thank you!