Asus X501A - Turns on, boots into windows but no display

Hi

Very weird thing is happening with my laptop. Turns on, boots into windows (i hear the windows login sound) but no display the entire time from the push of the power button.

- Laptop is Asus X501A
- Mobo "X401A Rev 2.0 HM70 chipset
- CPU: Pentium B980

What I have done/checked:

- reseat RAM and CPU
- tried other RAM and CPU
- measured CMOS battery and let laptop sit hours without CMOS connected.
- checked LCD screen to be wroking properly with other laptop
- powered on with and without battery, w/w-o keyboard, w/w-o HDD
- breadboarding the the entire laptop
- tested external monitors with HDMI and VGA (show no signal)

What could be the problem? Anything I could try "at home" ?

Never have I encountered a "no display" on a laptop that has a working LCD and everything else seems working fine also (as it boots into Windows).

Thank you