battery dies

yes I think so

The switch might be the problem. Next time (if it occurs frequently enough , try taking the key out , and opening and closing the door (as if you are getting out , but stay inside), then wait until you hear the 'chime' , then try tapping on the lock cylinder and see if it stops. IF the lever/sensor inside is sticking a little W-D40 (as I've seen recmmended here in the past) may help free things up. Either way , that is one way I can think of , to confirm if the switch is the cause. Hope this may help a little.Please reply with results and if that doesn't work , maybe someone else will have a better idea.