Turn on sometimes, power problem.
I have an iMac on the university lab and it is having some problem to turn on. When the lab is closed, all power is turned off. The next day, we open the lab, turn on the power and try to turn on the iMac, but this does not turn on. We realize that we have to stay the power cord plugged for a while, then remove the cord and then connect it again. Sometimes it turns on. If not, we repeat the process until it turns on. What could it be? I believe it could a power problem. But I'm not sure! Please, help me!