(Redirected) Dell Vostro 1510 does not restart after motherboard replacing (said processor issue!?)

Dears,

I have an issue with my laptop (dell vostro 1510). For the second time my screen became completely black. I could see nothing but the computer was working. I supposed it was for the same reason as the first time (video board burnt). I substitute it and when I try to start the laptop I just get three led among which the first one on the left is blinking. It doesn't go further and I don't have access to the bios. The diagnostic led codes say that it is a problem related to the processor. How can I test if the processor works? For me it is weird that with the old motherboard it was starting. I also tried to reset the processor on the slot different times. I don't know what to try more.

If you have any suggestion please let me know

Have a great day

Gian