I'm currently having this problem too. I almost bought another p/s but since it was turning on, I ruled that out. So now I'm thinking it's the motherboard. But since it is a 2011, finding the motherboard is quite the chore. If I fix it, the resale value is still really high, but I don't want to replace it with one that I can't fix myself, i.e. the newer mac mini computers. I may try to find a used logic board, swap out the parts and then sell it but keep my hard drives.