You get a limited number of attempts. If you enter the wrong code 3 times consecutively, the radio will lock you out for an hour (sometimes two hours). If you fail three more times after that, the radio can permanently lock, requiring a bench reset from a specialist.
Locking your Volkswagen (VW) Alpha radio is a common occurrence, usually triggered by a battery change, electrical maintenance, or a blown fuse. This anti-theft security system, known as "SAFE" mode, requires a unique 4-digit code to restore functionality. How to Find Your VW Alpha Radio Code vw alpha radio code