Power Failure AS Rockh310-cm UE5 Valley of the Ancient Demo

On a new build pc I was running the UE5 Valley of the Ancient demo & the program locked, the screen froze, the keyboard locked. So I had to shut the power off.
It hasnt worked since. No power. No light on motherboard.
I assumed that I had blown the power supply so I replaced it but it is still dead.
Nvidia Quadro M4000