Find the PMIC buck controller page. Verify that the IC receives its supply voltage ( VIN ) and outputs the essential +3VALW and +5VALW rails. Without these standby voltages, the power button will never respond. Step 3: Inspecting the Power Button Trigger Path
Locate the Step-Down Buck Regulators on the schematic responsible for creating the and +5VALW lines. i laj494p schematic better
Tools like OpenBoardView can open boardview files to complement the PDF schematic, offering a superior interactive experience. Find the PMIC buck controller page
Often caused by a failure in the charging circuit or the B+ rail shorting. Checking the ISL88739 (or equivalent) charging IC input/output signals is essential. i laj494p schematic better
Is the external crystal oscillator outputting its specified frequency?