PROBOOK X360 440 (RUMBLE  KBL) POWER ON TRIP, NO VCORE

3V 5V 1.8V 1V ALW ALL OK

VRAM VCC AND VGA CORE AS BELOW:

PCH CRYSTAL CLOCK Is also for 300mS shown below:

VCCSA and SCLK SEEN FOR A WHILE

Found Q4005 N-CH is not properly conducting even 5V gate voltage to output VCCST. Replaced VCCST Is in NORMAL RANGE. Now VCORE is 

in Normal Voltage level to boot Board.

For more waveforms captured in this case stay tuned to your own website....www.EasyMB.in