Dark screen problem

Question

So, I have an old PC that I haven't used for a year after buying because I deleted some sys files, and don't get me further than BIOS, so when I back I try to install new Windows.

After I successfully installed Windows on a USB-drive i found a tutorial and one of the steps was to change on BIOS order of drives(example):

So I did this and pressed F10 after this PC restarted and didn't save BIOS settings I remembered that I saw the line "BIOS battery low" so I searched what I could do, one of the tips was to restart BIOS pulling out the BIOS battery and placing it back after some time but I don't have this battery on my motherboard instead I see you can switch contacts"CLR_CMOS" with a jumper and this will reset BIOS as well. (I return the jumper after 5 minutes to the original position)

After I completed this step I powered up my PC and saw.... literally nothing on my screen it just was a blinking power button on the monitor. Help me fix this.

This is what I did after my problem came out:
change HDD and PSU(to better ofc)
try Speaker (nothing or he doesn't work(PC is around 10 year))
reset BIOS again
try place GPU and connect DVI to him
wipe RAM with an eraser
try another monitor
and waiting for veeeery loooong time