I installed my first car stereo well over 30 years ago and have done quite a few since. But I still managed to forget the "Step 1" that is never in the installation guide:
Before disconnecting and pulling out the old system, remember to remove your CD (or cassette, or 8-track, etc.) first!
2011 3.7 Convertible, K&N Typhoon CAI, Bama SCT Tune