My radio stopped working and the corresponding entertainment panel would not work. A day later, the car wouldn't start (dead battery) without a jump start. The battery itself then charged quickly land seemed fine, including the radio. The same thing happened two weeks later. I took it to the dealer. After an electrical checkup, he concluded that I needed to replace the battery, which apparently was also draining the battery. It took a few days to get the part and the installation, but all now SEEMS well. Conclusion: I suppose that any of several components could cause battery drainage (others have mentioned being careful to turn off climate control at night). But in my case, it was apparently the radio and its connections to the electrical system.
