Solved! HP ELITE BOOK 840G3 NOT POWERING ON,JUST FLASHING LIGHT ON POWER BUTTON AND ALL LED INDICATORS ON THE SIDE CONTIMOUSLY

[LapTrack Digital]

Last night was watching movies on my HP ELITE BOOK 840 G3 while on battery and when I was sleeping I connected it to the charger and leave on hibernation and went to bed.This morning I have found it just flashing lights on the power button and all side LEDs continously and trying powering it on, it's not turning on nor the fan spinning or any sign of life except for the flashing LEDs.What could be the problem and the solution

 

[mrmike16]

Reset the motherboard by disconnecting the battery and charger, taking out the CMOS coin battery, press and hold the power button for about 20 seconds, wait a few minutes, and put it back in again. Boot the PC with just the charger plugged in, not the battery.

 

[AlHuneke]

Make sure you get the service manual for this machine before you open it up. Follow the directions, especially ESD precautions. I would try just holding the power button down for 15 seconds first.