Hi @proodigy ,
Go back to basics and try a barebones PC setup, i.e. just PSU, motherboard with ram, keyboard and monitor and see if you can get into BIOS with a screen displaying.
If you don't get a display then hopefully when your 1st motherboard died that it didn't take the graphics card with it. I realize that you tried a different card in the new mobo, but am hoping that the original graphics card didn't damage the new mobo when you first tried it in the new mobo.
If you get a display OK go on from there by adding HDD and then seeing if it displays OK etc.