There is a simple twist in bulb for the backlight: ACDelco 16208443 GM Original Equipment Multi-Purpose Light Bulb, I found mine on Amazon, you can get them at most GM dealers for a buck or 2 more if you don't want to wait.
The trim around the radio just pops off, held in by a few clips, a small flat blade screwdriver slipped between the trim and the dash will lift it enough to get a grip with your fingers, then just pull gently, the trim ring around the ignition will also pop off, separate piece.
Once the trim is off, there are 3-4 screws holding the radio unit in, remove them and slide the radio forward enough to reach behind and undo 2 wire connectors and the antenna cable.
The faceplate is held on by a few plastic clips that snap onto the radio chassis, gently pry these up with your small screwdriver and the faceplate should come free with the small circuit board holding the build attached, twist out, twist in the new one and reassemble. Took me about 15-20 minutes total.