Question Help! The motherboard suddenly went black screen.

[lcldiy]

I cut two 7900x motherboards. At first, everything was working fine. Then disconnect the video cable, and when reconnecting it, the screen goes black but there is sound. The sound is functioning properly. It's a black screen, and the composite video signal is also black. Both motherboards have the same problem. After cutting, everything was normal. After using them for a while, suddenly the screen went black and there was a sound. Was the video chip damaged by static electricity?