Toshiba Satellite C850-P5010 Broken screen

Hello,
I've a Toshiba Satellite C850-P5010 laptop but now it's screen is broken now. So i thought of converting it into a media PC after some YouTube search. Now everything works well except BIOS.
I'm unable to enter into BIOS. So now I want to set my primary display as external monitor so that I can directly boot BIOS and can change OS.

Things I tried didn't worked-
1) Removed or detached display pins from display as well as from motherboard.
2) Tried to change primary display from my current OS (UBUNTU) form external monitor.
3) Tried to check for an option in BIOS on another machine of same model (cuz I had 2 laptops) but i found no option regarding display.
4) Tried to do hack with hall sensor using magnet just after pressing power button (It worked only once).

Current condition of my laptop - It's display is broken, so i detached that. It works with external monitor using HDMI or VGA only and don't even show BIOS.

My laptop BIOS is Insyde H2O older version.

Is there any solution so that it can change my main display to external monitor (permanently) or show BIOS on every Booting.

NOTE - MY LAPTOP DOESN'T HAVE ANY DEDICATED GRAPHICS OR DISPLAY CARD
AND I DON'T EVEN WANT TO GET MY LAPTOP DISPLAY CHANGED.