I have a 2002 Chrysler Sebring

I have a 2002 Chrysler Sebring. Recently, I noticed the key fob stopped working. Today, the car is sitting in my driveway and the interior light is on, and the headlights keep flashing repeatedly. I went outside I and I could hear that the doors were locking and unlocking by themselves. I put the key in the ignition and started the car. I then pushed the lock button on the key fob and it worked. I shut the car off and the key fob stopped working again. But the lights continue to flash and the doors continue to lock and unlock themselves repeatedly. What would cause this?