Was going to hard reset a MacBook Air from 2010, the issue could probably happen on all Mac though. This is what was done: So by holding down the alt-key (option-key) and the powerbutton while the mac is shut down you’ll get into a recovery state for both resetting and using time travel. In this
Being use to Windows and it’s lovely Blue Screen Of Death there wasn’t going long before running into Mac OS X own Screen of Death after messing around with an old mac. So, restarting the Mac.