Also done, and tried with another PSU.
im going to get him to test bench it outside the case, and worst case I can lend him a spare MoBo as I suspect that its a connection issue / something shorting or he's somehow fried the Mobo. As I doubt he managed to brick two CPUs and two PSUs
check everything is connected properly, if it's still not working unplug everything including ram, fans, gpu etc and try booting.