Hp probook 450 G4 Black screen with caps lock & num Lock Blink

[Mohamed-Mahdy]

I have a Pro-book 450 G4 > I7- 7 Gth since 2018 . i am always try to keep my laptop updated for ( windows which is 10 X64 ) and for drivers by checking the HP Driver & software website

i found that there is an update for the BIOS to 1.44 and another update for Intel management engine driver

downloaded them then start to install the ( Intel management engine driver ) then start to install the Bios Update > the problem happened here < after Bios Update , i think it didn't complete normally as the laptop make a restart then start to make beep sound with caps lock blinking ( 2 long blink + 2 short blink ) simulate with ( 2 long beep + 2 short beep ) the fan start to spin very fast without a stop

after 5 time the beep code stop but the blink continue as it ( 2 long blink + 2 short blink ) and the fan continue to spin very fast without a stop

i took a decision to disassemble the laptop to make a complete clean from inside ( dis attached every part from DVD , HDD , M.2 , RAMs , WIFI , fan , keyboard , top cover , mother board , heat think , cmos battery )

and left them for 3 night without resample again , then used an electronic dry cleaner (Q22) to clean the mother board and rams and all electronic parts , and changed the cmos battery by a new one from energizer (CR2032 V3.0 )

 it made a new blink code as numlock & Caps lock start to blink ( 5 long time ) then the fan start to spin then a restart is happen in a sign for a problem in power circuit as i think 

start to take out rams and change their places then it made a new code ( num lock & caps lock blink 4 long time ) and the fan start to spin very fast without a stop and the battery led some time it be a white led and some time with orange led and some other it is turned off 

now i don't know where is the problem , is it in BIOS Chip ? or in power Circuit or in other part , how to find the cause and what is the step to solve it ?