Disclaimer: Schematics are for educational and professional repair purposes only. Circumventing security or modifying hardware may void warranties and violate local laws. Always follow ESD safety precautions.
Already tried:
Using a multimeter, check pin 5 (VIN) of PU8 for 19V. Check pin 3 (EN) for 3.3V. If EN is missing, the EC is not booting, pointing to a BIOS or EC firmware issue. ms-16j91 schematic
It utilizes a common charging IC (often from the Intersil/Renesas ISL series) to manage the battery and AC adapter switch-over. the EC is not booting