A friend of mine just gave me a bunch of computers that had been donated to him. Unfortunately, none of them are working and I was asked to help fix them. They are all 20 inch iMacs from 2009. EMC 2316. None of them have operating systems on them. When I go to power them on, they make the startup noise, a gray screen comes on, and then the system shuts down. I have attempted to power into Target Disc, Single User, and Safe Mode. I suspect that it is hardware related given that the system shuts down before I can see it looking for the OS but could be incorrect. Any advice is greatly appreciated.