1 HP EliteBook 840 G4 - Power button light on but no boot/POST after BIOS reprogram
I'm troubleshooting an HP EliteBook 840 G4 that is effectively 'dead' with only the power button LED lighting up when pressed.
I have already performed the following troubleshooting steps without success:
1. Hard Reset (Drained power for 60 seconds with battery/AC disconnected).
2. Tested with AC adapter only (internal battery disconnected).
3. Reprogrammed the BIOS (flashed known good firmware).
4. Isolated components (disconnected SSD, Wi-Fi, and secondary boards).
5. Attempted boot with CMOS/RTC battery disconnected.
The laptop shows NO blinking patterns on the Caps Lock/Num Lock keys and there is NO fan spin or display activity. Since the BIOS reprogram and basic isolation didn't work, I suspect a power rail failure on the motherboard.
Are there specific voltage rails (3.3V/5V/CPU_VCORE) or power management ICs (PMIC) known to fail on this model? Any advice on board-level measurements to take next would be greatly appreciated.
Cette question est-elle utile ?
@stevenmutebi Are there specific voltage rails (3.3V/5V/CPU_VCORE) or power management ICs (PMIC) known to fail on this model? No, there are not. We need to know which motherboard your computer uses. It'll be printed on the motherboard. You sure about the firmware being good?
par oldturkey03