Add or remove a stick of RAM. Obviously if you have one stick in, add one and if you have two in remove one.Power on the Mac and immediately press and hold command-option-P-R.The system will restart with the ‘bong noise’, allow it to do this 3 times. On the third ‘bong’ you can let go of the keys.
Heeft je vriend (of jij, toen je begon te klussen) deze stappen allemaal doorlopen?https://support.apple.com/nl-nl/HT201065
Ziet het wachtwoordscherm er zo uit?Zo ja, dan is dit de oplossing:Bron:https://discussions.apple.com/thread/6727831
Applesetupdone