Audio Systems: 2000 Impala stereo, power door locks, odd problem

Question
The radio in my son's 2000 Impala stopped working.  There is no sound from any speaker when turned on.  There's an amp in the trunk under the rear deck, two speakers in the rear and two up front in the doors.  This a factory installed system with CD.  The radio has power and seems to still control some of the auto's settings, such as the automatic light dimming, power door locks, etc.  The odd thing is that when the radio is off, occasional static noises come from the right rear speaker, but only when off.
Where do we start to troubleshoot this sort of odd problem?

Answer
remove the battery to reset the system for 10 minutes
this is a BCM problem the radio stops the audio when the vehicle is going to send a warning using the front speakers
leave the key on the ignition and open the door to see if the door chime is still working
if this don't help  the radio needs to be remove and test outside  
sorry i can not help you more