I just upgraded my Mac Book Pro to Big Sur. After installing, I tried to login and it showed a loading bar (normal). However, someone in the loading bar, the screen goes black and then a new screen appears and says, “the computer restarted because of a problem. Press a key or wait a couple seconds for the computer to restart”. I have tried going into safe mode, recovery mode, Diagnostics, literally you name it, and I just cannot get anything to work. Please help