engine fan will not shut off

Last night I drove home, shut off the engine, exited the car and locked the car. All systems did its normal "thing" to indicate a successful lock with the exception of the engine fan. I could hear it still turning. It seemed odd as I had never noticed that before. I got back in the car, turned the engine on drove around the block. Repeated the steps of turning off the car and locking the car. Fan still running. I went inside and waited thirty minutes, fan still running. I waited another thirty minutes, fan still running. It was very late by this time so I went to bed assuming if it didn't stop my battery would be dead by morning.

Sure enough, this morning the battery is dead (but the fan has stopped running, lol).

Any suggestions other than take it to the dealership?