I had a similar issue with a Mercedes Benz I had.... Something draining the battery..
But I had to go through every fuse, and use a 2 wire lead with a light bulb attached to it.
(With the car off of course) You pull the fuse out, and touch the leads to the fuse plug... If the light bulb lights up, then its something attached to that fuse that's still on, and thus draining the battery.
It's time consuming, but it could possibly help you determine if something in the car is draining your battery.
This might be a thought to consider