Notebook Boot and Lockup

Serial number: Edited
Product numer: 38Y76PA
My laptop crashes when I try to plug it in, within 2-3 minutes or sometimes an hour. By "crashes" I mean the screen just goes grey in color and all background activity crashes(with no cursor on-screen). Rarely instead of the grey colored screen it shows some BSODs.

Here are the following codes I have got:
page fault in nonpaged area
kernel security check failure
kmode exception not handled
critical process died
memory management

I tried the following fixes:
purchased brand new RAM sticks, ran /chkdsk scans, clean installed windows, cleaned motherboard with IPA 99%(no burns or discolorations),  ran '/sfc and /DISM restorehealth' scans and found no corrupt files, repasted the chip, stress tested GPU, Clean installed graphic drivers(using DDU Tool). 

Also used tools like "WhoCrashed" to analyse minidumps, but the tool only recognizes the minidumps of BSODs. There are no minidumps of the grey screen crash.

Also noticed how the two indicator LEDs on the side of the laptop, One representing drive usage and One representing power. The LED that represents drive usage blinks randomly when laptop works normally. But when the grey screen crashes, It stops blinking. Even when trying to Boot after that, I cannot even boot into BIOS sometimes. The power LED alone remains on.