My PC won't start but the lights on the motherboard are on

Hello, so I had this PC built from July and it worked just fine until one of my friends wanted to play a game on his own PC and moved my graphics card into his case, after he went on to put it back into my own, my PC wouldn't start, not even a slight spin on the fans but the lights on the motherboard are on so I suppose the power is there, I checked and all the connectors are where they should be, we also connected 2 pins to a motherboard connecter to see if the SPU was working (I have an EVGA 650 GQ)
We've tried everything we knew but no result, we tried even switching SPU's (he has a EVGA 750 G2) and the rams but we got the same result, and now his PC won't start as well, we don't know if it's either the power supply or the motherboard. My motherboard is an ASUS Prime B250-Plus Socket 1151/DDR4/S-ATA 600/ATX and my rams are 2 x 8GB Corsair CMK16GX4M2B3000C15 Vengeance LPX DDR4 3000 MHz C15 XMP 2.0

 

Sounds to me like it's the power supply. Try to disconnect all power connectors, except the two that go to the motherboard, remove any and all expansion boards. You can also try to switch a power supply you know if good, to the system that's not working. Again, only the two connectors fo the board.

 

I think so too, but could it be that the power supply made my mobo break? Like it somehow short circuited it? And possibly my friends mobo as well because his SPU is fine but the PC still won't boot

 

I'm not really sure what you mean