System PIN lock appeared for no reason
I was using my MacBook and I was logged in to my profile, when suddenly the MacBook restarted and is now asking me for a 4 digit PIN code. Please Help!
It sounds like your Mac is being remotely Find My Mac locked. Do you know any unlock code, have you set that up in the past?
You can try that.
Do you have the MacBook bought second hand? Maybe the original user made a mistake by locking it?
You can ask apple support for help but they will not help you without original proof of purchase documents