Asus Laptop Black/Blank screen (Boots up but NO BIOS / any displ

One day, when I booted up my laptop. It boots up normally, but the screen stays black/blank. No bios, windows logo, anything appearing on the screen.

The lights on the laptop are flashing, cd-drive is working, I can hear sounds from the hardware.

I have tried removing battery and cable, and holding power button for 60 seconds. I have put everything back inside, still not working.

I have also tried to plug in external monitor. Doesn't work.

Could this be a hard drive problem? Since my computer was telling earlier that my hard drive was full, even though it wasn't. (might be broken?)

Any help would be appreciated.