Question Laptop black screen, works with external monitor

May 4, 2021
MSI GS65 screen went black when watching a video, everything else (keyboard, fans, usb transfers) works and I can see with an external monitor connected.
When I reboot without external monitor, the MSI logo flashes for a brief moment and then its black. I cannot enter safe mode or bios either. With external monitor on reboot, MSI logo flashes and eventually shows log in screen on the external. Cannot see safe mode/bios on external.

Also, the laptop display is not detected as a display, there's only 1 display which is the external. However based on suggestions online disabling intel graphics could help resolve issue, which i tried, the laptop screen is detected, but it is black still, even after rebooting. The display properties of the screen is odd though, with 1 hz refresh rate. Have tried duplicate/extend settings but still nothing.
MSI support suggested clean installing through safe mode but I am unable to access safe mode. I have tried updating and resetting EC. I have checked and reseated ribbon cables. Last resort is to factory reset before sending it in for repair. It is out of warranty as well.

Does anyone know what the issue could be? I disassembled to clean the fans last week and it has been working fine, though does not seem to be motherboard issue or GPU issue or LCD issue as all seems to be working except for the black screen after the boot up. Could it be the intel driver as that seems to be the only thing to allow the laptop screen to be detected?

Any inputs appreciated. Thank you