Dell monitor not detecting working PC

[phleexiou]

My grandfathers PC has been working just fine with this monitor for months. One day it flickers, and finally goes to simply stating “no hdmi input”. Monitor works just fine with other computers, even with the same cable. The computer works brilliantly with other monitors, including my personal Dell. For some reason his computer and his monitor simply refused to talk to each other. So finally we decide screw it, let’s buy him a new one. A Dell S2721HN. Same problem. Scans for signal, then says no hdmi signal from device. 
 

 

I’ve done driver updates and reset the PC’s Bios, all the windows updates, swapped cables, ports, the whole 9 yards. Still no dice. Short of buying him a new computer, what might I be able to do to get this thing working?