What happened to my personal computer

Good evening dear steemians. that's what happened to me this morning.

I woke up this morning i turned on my pc
It starts well (LEDs, hard disk noise ...) but its screen remains black.

I tried to remove the battery, connect an external monitor, disconnect the ram strips one after the other, but it does not work.

I looked on the internet about the problem, and I found several possible causes.

So It was necessary to pass to the material part. then ihad dismounted my pc.
the problem is either at the RAM level or at the BIOS level.

I replaced RAM but the problem is still.so the problem is certainly at the level of bios.

I have detached all the components to get to the bios and clean my fan also.

I found the battery of the bios runs outI have replaced it.
also I found the CPU thermal dough is almost finished,so I inject a new dough on the processor.

after that I cleaned the fan well from dust,and I gathered my computer.

my computer is working well now, i'm happy because i have a lot of work to finish on the pc.