This EXACT issue is what happened to our 06 E53.

Parked for 2 months. Battery died (internal short! Even a multimeter denied the battery even existed lol).

Replaced battery, got everything running, driver side rear door won't open from either side but everything feels like it's functioning.

I'll try the bypass button handywork this evening when it stops raining.

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2006 BMW X5, 3.0i - 161,000 miles
2003 Ford Mustang GT - because having Two cars that keep dying seemed more exciting.