Mac Mini (late 2014) macOS Sierra 10.12.5 (16F73) 2.6 GHz i5 8 GB RAM 500 GB SSD Intel Iris 1536 MB Someone I know bought a used 2014 Mac Mini from a computer shop. It's in very good condition, barely used. It's running the latest Sierra, I updated everything on it. I made a new user account but didn't reinstall the system that was on it. My friend has had it for 2 weeks, and at least 4-5 times the following has happened: he walks up to the sleeping computer, presses Space and the screen (3rd party) remains black, no response. The fans are spinning and the air coming from the vents is warm. Caps Lock key lights up when pressing Caps Lock, though sometimes even this won't respond. Pressing the Volume buttons on the keyboard (wired 3rd party keyboard) doesn't make the "Pluck" sound, so it's not an issue with the screen. Each time this happens, we need to hard reset and boot it up again for it to work. The only consistent thing is that when the computer goes to sleep, it sometimes won't wake up from it and requires a hard reset. I can't find anything suspicious in the console, I don't know what to look for. There's an option to return the computer for a full refund for a few more weeks, but there is no Apple warranty. The seller says this is 100% not a hardware issue, he is offering to reinstall macOS. I'm certain he wouldn't know if this is hardware or software, for all we know this can very well be a hardware issue. Should we run some tests, let the seller clean install macOS, and hope that this is a software issue, or should we just return it and get rid of it, and just buy a new Mac Mini with lower specs? He bought this for the exact same price as the current base model Mac Mini that Apple is selling. The only benefit is that it has twice the RAM and an SSD, but of course it's used and out of warranty. Is this price even reasonable?