I had the battery in my Z28 changed today (not at a dealership), and
when I got it back, the stereo didn't work. I checked with the service
consultant, and he checked with the tech, who said I needed to go to
the dealership and see if they could get me a code. Like I have time
for that. So I Googled, hoping to find some clues about how to deal
with it. I got everything I needed from some old posts in this group,
and a few minutes later, had my stereo working.

Thanks! I should hang out here more often. :)