Check the overhead dome lights are Off, very easy to leave one on. The battery is under warranty, maybe see if a store can load test it after it's charged with a batttery charger. It's possible you have something in your car drawing power more than it should when the key is off. Disconnect the battery, check for low ohms reading across the cables. If you find less than 300, A good place to start is disconnect any aftermarket lights, stereo, etc. Check for a radar detector, Ipod, phone, cigarette lighter that stays on. I once had a faulty power mirror switch in a Dodge kill the battery. I disconnected the battery, checked from positive to negative cables, found 30 ohms. Then I looked in the schematics for circuits that were "constant power" and I pulled and reinstalled fuses on at a time, found circuit, checked its schematic unplugged switch, felt lucky.