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As for the battery drain check that both the interior lights on the doors goes off after you lock the car. It's easy to accidentally hit the light switch with your leg when getting in/out of the car so that it stays on all the time.
I'll second that - the interior lighting has to work just right or it affects a lot of other systems, including the door locks & alarm system. Any light that doesn't work perfectly and like the others should be replaced and the wiring should be double-checked.
The other suggestions should all be checked if you find a battery drain.