Hello,
I'm having the same problem, sometimes it appears that it has no hardware installed, sometimes the turn on option is locked, and sometimes it works normally.
But when it "works" I'm using it and out of nowhere it locks the mac, sometimes it turns itself off and when I try to start loading, needing all the time I'm restarting it works again, but I use a certain amount of time and it hangs again if What happened to you?