Copied directly from SI:
"New Vehicle Limited Warranty
Bumper-to-Bumper (Includes Tires)
• Coverage is for the first 4 years or 50,000 miles, whichever comes first.
• Corrosion coverage is for the first 4 years or 50,000 miles, whichever comes first.
• Rust-through coverage is for the first 6 years, unlimited mileage."
So depending on when you took delivery, you might still be under warranty. If it's out by time, you might be able to get your local dealership to goodwill for you.
On a side note, the only special procedure that needs to be followed after replacing the battery is to be followed IF there is an issue, but not mandatory unless there is.
# Power windows calibration:
2.1. Repeat these steps for each window.
2.2. Turn the ignition switch to the RUN position.
2.3. Press the power window switch to the down position. After the window is in the full down position, press and hold the switch in the down position for 3 seconds.
2.4. Press the power window switch to the up position. After the window is in the full up position, press and hold the switch in the up position for 3 seconds.
The other one I found was if you lose On-Star communication:
After completing ALL repairs to the vehicle, you must perform the following procedure:
1. Move the vehicle into an open area of the service lot.
2. Sit in the vehicle with the engine running and the radio turned on for five minutes.
3. Press the OnStar® button in the vehicle.
4. When the OnStar® advisor answers, ask the advisor to verify the current location of the vehicle.