"Did you unplug the battery from the car first? And did you need to add the metal sleeve that came with the radio?"

Yes, and Yes. I detached the negative pole, and the sleeve slides into the OEM radio hole to secure the new radio.

Look at the second photo in my above posting. It shows how the sleeve slides into the orig hole.

Probably didn't have to unplug the battery, but why take a chance of a short while playing around with a bunch of wires.