Any Mercedes dealer will provide the correct 3 or 4 digit code to activate
the radio upon proof of ownership (registration/title).
If the radio is without power from a battery for a while and then repowered
it may require you to let it reset for either 10 minutes or 24 hours(?) with
the 12 volt battery power and the radio turned ON.The screen will read
"WAIT" [instead of the prompt "CODE" (it's asking for the code)].
If it says WAIT, let's hope that particular Becker has the ten minute timer!