Here is what went on before I got into this problem. I have Mavericks on both the main system and a second partition, I had some trouble not seeing avatars here on Macrumors so I restarted into the clean Mavericks partition, this didn't help either so I restarted into the main System by holding the Shift key. I got to see the spinning wheel and the normal Apple logo together with a loading bar, the bar didn't progress and after about 20 seconds it vanished. Then another 10 seconds and the Mac Mini (Late 2012) shuts down. When I press the On button on the back again I get exactly the same. Nothing I tried helped, it is stuck into the safe boot process and shuts down each and every time. No key combinations work. *Holding Option to have the boot Manager show up does not work. *Resetting NVRAM/PRAM does not work. *Resetting the SMC does not work. None of the key combinations work, not on a Apple wireless keyboard nor on a wired one. I also removed the RAM for a bit, thought this would clear the NVRAM, NOT, I do have the old RAM and that's next. Edit: Installing (Original) RAM didn't help either. I am pretty sure it is not a hardware failure, I am pretty sure it's just stuck in this Safe boot loop. A couple of months ago I tried to install Mavericks on an external, It finished Installing (partly) and whenever I tried to get into recovery I got the message over and over again that the Install failed, even after deleting a certain Install Folder on the External, so I guess this is probably a Mavericks problem. The HD is not easily accessible in a Mini otherwise I would try another HD, an external also won't work since I can not choose the external. I was thinking about using Target Disk Mode but I think the problem is set in the NVRAM and I can't clear that if I startup this way, if there was a file to delete it would be easy but I think this is not a solution here. Any help is appreciated. Normally I am the one which helps people here but right now I don't have a clue what to do next. (OS X 10.9.1 latest beta) Mac Mini 2012, 8 GB RAM Update: weird but now I could startup using the Option key with a wired keyboard, problem not solved yet but it is at least starting up from Recovery or a different partition.