I just bought a new iMac 5K Retina yesterday evening. Everything went fine, it looked great! Today (after less than 24 hours after buying it) was going out and turned it off (Shut Down). Came home about 3 hours later and tried to turn it on. Nothing. I took off the cables and waited for a while and tried again. Nothing again. The new iMac is completely dead less than 24 hours after I bought it!! I've had an iMac for 7 years without any problems and this one died within a day! Does anyone have any ideas what happened and how to fix it? Unfortunately it seems there's nothing I can do and I have to take it to Apple service, but would you ask for a new iMac if the one you just purchased stops working within 24 hours?