BQ24780S has no REGN (6V). Schematic shows REGN requires 20V on ACDET (pin 5). ACDET reads 2.8V (should be >2.6V). Replace voltage divider RA1/RA2 (1MΩ and 120kΩ) – now ACDET = 3.1V. REGN appears.
Laptop now powers on but no display. Using schematic, verify VDD_CORE = 0.9V, VDD_GFX = 0V. PGOOD from GPU VR is missing. Replace MP86945 driver – fixed. Laptop posts. 17ips72 schematic
Using the boardview, locate PF1 (fuse near DC-in). It is open. Replace it – still dead. BQ24780S has no REGN (6V)
Schematic shows +3VALW generated by TPS51285 (U2). Enable signal EN1 (pin 3) is low. Trace EN1 through a diode to EC. EC is dead due to liquid damage. Replace EC (IT8227VG-192) – +3VALW rises. Replace voltage divider RA1/RA2 (1MΩ and 120kΩ) –
Schematic indicates the main 20V rail splits into +VBUS and +VAD. Using a thermal camera, +VAD shows a hot spot at PC101 (0.1µF, 25V cap). Remove it – short gone.