Needing Help

[UGP Studios]

So, My friend brought me his Gaming PC today to fix... I hope it’s something fixable..

SPECS

Core i5 8400

TUF GAMING H370-Pro Gaming

and an EVGA 700 B Power Supply

( I have eliminated the RAM as a culprit already)

So, when the power supply is flipped on the onboard power LED, flickers randomly and the power button does nothing... I have tried unplugging all the fans, removing the RAM, unplugging the power supply, resetting the CMOS battery, removing all PCI, and PCIE, in varied orders yet nothing has fixed it, I have also trying to see if the SATA drives are shorting the board in anyway. I tried another power supply but that test was inconclusive due to not having a spare 700 wat power supply on hand and only having a 500 wat power supply. He said that the board powered (only been powered on once) on and hasn’t worked since he shut it down.. If he just needs a new board I will tell him. But if there is anyway to troubleshoot it even more or anyone has advice... I’m open to help.