possible cmos issue

Daughter pc stopped working(6 + years old i5 system win 10). An infinite loop and no screen booting.
She brought it to mine after some checks i removed a video card and replaced the cmos battery. Replace power cable and a possible loop and then pc booted up into a cmos bios screen which i pressed load normal defaults or something and pc booted or went to win 10 logon screen. Sorted
No because i replaced video card rebooted and then nothing, and still nothing.
So i hope this makes sense, now pc is fixable i think but just dont know how.
So rather than daughter spending £400 on a 2nd hand pc, how can i fix this?


Cheers

its got onboard vga and another video card cant remember make model. so i removed the video card and reset the cmos by placing a new battery. at that point we got a boot up into the win logon screen.
replaced video card, no boot up. removed video card again and no boot up still, removed battery for cmos, 2 mins later replaced batttery, but still no boot up

Megahertz07 said:

When you say it stopped working, you mean nothing works? Can you boot into BIOS?
Is your Daughter pc a desktop or laptop?

As you removed the video card and it worked, it may be a power supply failure.

Apparently everything worked fine, then went "off". She tinkered with it, then brought to me.
I turned pc on, no screen no bios screen, just a loop from the ssd as it wanted to boot but nothing. Then i read jump the cmos, so removed video card, removed battery waited 2 mins, replaced with a new battery, didnt replace video card can use onboard at that point i got aboot into bios setting change, clicked whatever then win 10 logon screen appeared. Hey presto, ALAS once i replaced the video card and checked the boot nothing, removed video card again, nothing.

I must add all the fans work ok, psu fan works,dvd drawer opens but no screen or boot up