Remove the two screws in the pocket underneath the ash tray. Don't take the ashtray out they're directly under it.
Now what is holding in the whole piece from the shifter to the top of the deck are retaining clips. You might be able to pull it off with your hands or you might need something flat and thin, such as a putty knife or similar. Mine comes right off but I've had mine off a lot of times. You shouldn't worry to much about breaking anything usless you put to much stress on one point. Try working from around the shifter on up.
Once you have it off you can move it over to the pass side of the car or take the harness off the cig lighter and the whole thing will come off.
Next there are four screws holding the deck into place. Take those out and your home free!
So thats what I was doing wrong!! I thought I had to get the screws inside the ashtray compartment off, and then the trim would loosen... I guess I just had to tug on the trim a bit... just too scared to break it.\
I would only recomend disconecting your battery if you are actually taking the individual wires out of the harness, which you will not be doing. Just make sure you dont jam and metal inside the harness, or you will get sparkies = no good. I would first take off your drivers door panel and see what color the wires are, so there is no guessing when you get behind there. However it may be apparent that two wires are disconnected, or just one for that matter, and the signal is not completing its path (remember electric signals of any sort must run from source to ground, somewhere in the setup). Good luck.
If you cannot find anything apparent, I would say that your next step would be to take a test light or voltmeter and see if the deck is putting out any voltage to the speaker... if it is not, then it is probably your head unit.