After disconnecting the battery on my 1993 405 I foolishly entered the wrong radio security code. All it does now is show "SECURITY" on its display. What I need to know is how to get it back into a state where I can enter the correct code. Is there a button sequence or is it just a case of waiting for a period of time? If I just need to wait does the radio need to be switched on or off. Any help would be greatly appreciated. Thanks in advance Richard