The second main part of the radio is located on the upper right side in the trunk behind the carpet panel. A bolt in the bottom with a 10mm head holds it in the bracket. Remove the bolt and the module will slide out. These units have a lot of small electrolytic capacitors that leak and cause all sorts of problems.

Do you have the CD player and if so is it the Alpine unit that has the interface module (MX3192, 002 820 3289) screwed to the bottom of it? Bad solder connections on the DIN buss connectors inside the module can cause radio problems as well. I've got 2 interface modules and both bad cracked connections on most of the pins where they mount to a small circuit board.