I have a 2001 galant, the battery went dead and when i installed a new one the radio wanted a code of course. i entered three codes and it turned off. now when i turn it back on it says off on the display. i have taken the fuses out, unhooked the battery cable and even unhooked the radio. i let it set for about 12 hours with no power supply at all, but it still says off.

 

Turn your key to the accessory position and let your car sit for about an hour, your radio will then reset itself.