Try a proper cmos reset
Unplug the computer and PSU from the outlets and all power
Open the side of the computer
Hold the power button for 15 seconds with everything UNPLUGGED
locate on the board the CMOS battery, Looks like a watch battery, typically under the GPU or near the PCI slot
Remove the battery, when its removed, HOLD THE POWER FOR 15 SECONDS
Now put the battery back in
plug in the computer and everything back in the way it was
boot up the computer
this should give you video, if not then your GPU may be having issues or the computer
if its just the monitor, it needs to have display input in order for it to display anything or sense an input
Connect your computer and devices to electrical outlets, and turn them on.