I've been trying to install Ubuntu server on my Mac mini 6,1 with no success. However now I'm stuck and can't even reinstall OSX from a USB key. I've created it on my MBPr, and tested it there : it works fine.
Now when I try to boot from it in the Mac mini, I get a grey crossed-circle and the Mac mini shuts down.
Does anybody knows a way to fix that ? Thanks