I was testing out the functionality of Find My Mac lock on my iPhone last night and locked it with a passcode. However when I return back to my Mac, I was unable to boot it up to the lock screen as supposed. It would show the apple logo and the loading wheel, and then just shut down on its own! I've tried several methods, like holding down command+option+P+R or shift key to go into safe mode, but it can never boot through, and will just shut down on its own. I'm terribly puzzled, HOWEVER, I am able to boot into windows though. Can someone please advise if they encountered the similar issue? Thank you very much!