Car APS95BT2 2-Button Code Learning Transmitter "mercedes radio decoder" Questions

...mercedes need radio code? First make sure that the code has not been noted somewhere within the car (underneath the ash tray, glove box , rear of sun visor etc)  To see if your code is available ...

I've just changed the battery today, then the radio doesn't work. I don't know the radio code as well. what should I do? Hi a dealer should be able to give you the code if you get the serial number ...