Ok, my friend went over to his other friends house. They plugged in the PC and when he turned it on, sparks came out of where the mouse plugs into the case in the PS/2 cable's end. Now the PC won't turn on. Now as most of you know, I suck **** at troubleshooting; So I need your help with this. Could it be the Power Supply? I'm going over to his house tomorrow to replace the PSU but I want to know what else we could do. Or if replacing the Power Supply will damage it further (in case the motherboard is fried). Would also appreciate some speculation as to what could have happened.