My 1432 says "WAIT" ...I have left the radio on all night and it still says wait...does the ignition have to be on ACC, or can I just leave the radio on by itself during the wait period?

Do I really have to leave my radio on, and leave the car untouched for a full 24 hours?? O_O

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Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles