So I think the motherboard from my Pc is broken, but it could also be the processor and I don't really know how to check it given that I don't really know about pcsand I don't have any replacement for that pieces so I can't just try to change it.

This is what happens: turn it on, everything starts to work, nothing appears in screen, it won't do the beep it does when it starts and it will be running like that until it eventually shuts itself down and on again. As far as i have seen this can go on and on and on.
Also, from time to time it will show the part where you can press a key to enter the bios or to select the boot (don't know if that screen has a name) and it will enter automatically the bios but only the background from it will appear, and not the menu. In this case it will also shut itself down (in less time) and on again.