Did you leave a light on? It's the most common reason for an unexpected dead battery. Or you have an electrical system problem. The dealership will probably find the reason. Then you'll know.

There was a light or device left on. Were all the doors closed properly, dome light in the off position, cel charger left on...

if you have an aftermarket sterosystem a bad ground could be draining the battery. battery being drained repeatedly will trash it.

battery could have just been defective to begin with though.

Why worry about it. It is under warranty and the dealer will figure out what is wrong. You can ask when you pick up the car.

It took several minutes before it started with the jump. I took it to the dealership and dropped it off and used the nightbox to put my keys in. I took it to the dealership because that is where I got the battery. Car only has 20,000 miles on it. What could be wrong