: Passes through the protection MOSFETs (PQ1 and PQ2, usually controlled by the charging IC). If +B+ is missing or shorted to ground, the entire board remains dead.
Corrupted RAM filtering capacitors pulling the rail to ground. la-d401p schematic
The "Always-On" rails. If these are missing, the laptop will appear completely dead. +1.0V / +1.05V: PCH core power. : Passes through the protection MOSFETs (PQ1 and