Car lights left on auto. Dead battery?

So I have a 2009 Nissan Altima and I left the lights on auto. It usually takes about five minutes for them to shut off. The next morning when I tried to start my car it wouldn't start. This is the first time I left my car lights on auto and the first time it has died. I also left a cord plugged in. I believe it's called an auxiliary cord to play music off my iPhone. It does not charge my phone or anything like that. The car was turned off. Which one of these were the problem?

- it's a fairly new battery by the way.

Have your battery tested

Try to test connection. If it seems tight, tap the battery terminal (wires where battery connects with car) with a heavy wrench or hammer to move it around a little, maybe there's corrosion or salt built up on terminals.

The bad news is that when a battery is discharged like that, it will never charge up the same way. The lights pull a great deal more power than an iPhone.