this seems to have happened 4 times since we have owned the car. typically when you exit the car or just open the door the power to the radio and windows are de energized. for what ever reason this is not always the case with our car.
it happens like this, she is on the phone so the radio volume it turned down, its on a Thursday so the car will sit over a long the weekend. come Tuesday (she works from home on Friday and Monday) the batt is completely drained.
This last time, I put the charger on it and noticed static coming thru the speakers. I was unable to turn the radio off or on. the dash responded to the power from the charger if the key was on but no lights on the radio just static. I disconnected the batt and continued to charge it. once it was charged up I reconnected it and the radio came on. I was able to turn it off this time.

 

Chafed wire / bad relay / water in trunk / ...

 

I know this is an old thread, but I'm hoping someone can help. 2002 Xtype my radio wont turn off, and my positive battery cable is getting burning hot when I run the car. This all started after replacing the battery, and the trunk got soaked in a rain storm due to leakage. Its got the nav, 3.0, cd changer...

Thanks,

Darren

 

Try asking in the right forum...