Solved! Can't open bios. Changed to legacy boot Toshiba p75 a 7200

[Kairat]

Can't open bios. I felt fast boot shouldn't affect when nothing is attached. Get straight to underscore and a black screen.
What to do now

Tried batter removing overnight. Got g1-3 and 5 pins. Shorted them all to drain the battery and reset to factory defaults. Feeling keeping old os is better compared to a dead laptop.
Found many questions of that kind. None worked. Hoped overnight draining would work. It didn't

Now I know why you need smartphone

On the bios page it said legacy settings can't be changed with reset to defaults.

 

[hang-the-9]

Can't open bios. I felt fast boot shouldn't affect when nothing is attached. Get straight to underscore and a black screen.
What to do now

Tried batter removing overnight. Got g1-3 and 5 pins. Shorted them all to drain the battery and reset to factory defaults. Feeling keeping old os is better compared to a dead laptop.
Found many questions of that kind. None worked. Hoped overnight draining would work. It didn't

Now I know why you need smartphone

On the bios page it said legacy settings can't be changed with reset to defaults.

You can't enter the BIOS screen or the system now does not boot? Your title and what is happening don't match. You can't go to the BIOS page if you can't open BIOS. What exactly happened here, did you change some BIOS settings and now it does not boot? You seem to be skipping a bunch of things that happened, what does keeping old OS have to do with getting into the BIOS?