Arthaus:
I want to express my profound gratitude to Udemzyudex, for his kind assistance, despite being choked up with work, and I can truly affirm that he is a technician's technician. Despite doing his best regardingmy ZBOOK complaint, he went as far as flashing the BIOS chip and when it seems like the problem persisted, he sadly told me that we were out of options. Now to the good news, having seen him at CV, Ikeja on Friday, my mind was restlessand by Saturday, I had this prodding to boot the system. When I did, it still showed same glitchy screen as usual
which had also shown after the BIOS flashing. After few seconds, I just intuitively pressed the "enter" key, and to my surprise, the screen went dark, then lit up albeit blank. After a while, I saw the dotted circle, followed by the "please wait"... Next thing I saw was the login screen and pronto, I logged in. Now with his guidance, I was able to switch the hard drive to another system where I installed windows 11pro. The initial OS was windows 10pro. After swapping back the HDD to the HP, I saw the HP logo briefly on the boot screen. Mind you, the screen on booting no longer showed anything like esc or f2 options to get into BIOS or boot options. Even now I have done a clean install, the screen went glitchy briefly on restart before finishing the boot sequence properly. I will keep you guys updated as soon as I am done with the windows update processes online. Special thanks to Fixitng, who gave me potential troubleshooting directions as early as 6am on Thursday too.

Glad that udemzyudex assisted you in sorting out the issues. Please keep us updated. Thanks.