well i think you misinterpreted
remove the gpu connect the monitor to the motherboard's vga port and check for video signal if you get the signal and the pc boots properly its just a faulty gpu
if not try removing the ram and cleaning it with an eraser and REinsert it before you boot again.
try it without the gpu first then if it works try it again with the gpu
reset the cmos check if the bios boots
and do check if the cabinet speaker is connected as most motherboards give signals in somtehing like a morse code to identify the problem the key can be found in your motherboards manual
if you did all this with no luck then id probably once check the system with just the processor and ram on board an then with another psu
this way you can isolate the faulty component
if the problem still persists then most probably the motherboard is dead.