Looking for some advice from the board! I'm really well versed in E36-era BMWs but am new to the E53 platform. I have an Oxford over Black X5/5MT that I'd really like to keep through the winter, but have been running into some gremlins.

What happened:

• Left an interior light on for a few hours in the parking lot while I was at work. Key would not unlock doors, assumed battery was low. Car did start and didn't require a jump, but lost most broken functions below. This was maybe 2 or 3 months ago.
• Key was able to remotely open the hatch for a few days, then that stopped working as well.

What's broken:

• Wireless key functions (lock/unlock/hatch release)
• Central locking button does not work
• Hazard switch does not work
• Front windshield wipers do not work (rear wiper does work though)
• Automatic interior lights do not come on when doors are opened
• Hatch release switch does not work

The wipers and not being able to get in the trunk are the biggest pains in the ass right now.

Some theories I have:

• GM3 issue. Although I'm not sure if it would cause all the issues above.
• Dead key issue. Not sure what that actually would do to prevent the interior buttons from working.
• Transport mode. I've tried to code it out a few times with a friend's tablet scan tool, but it didn't seem to do anything.
• Fuses/grounds? I checked both fuse decks in the glovebox and in the trunk and didn't notice a difference.

I'm hoping you guys can help me to dial this in and figure out what the issue is! I may just take my spare key apart and solder in a new battery, but want to see what the board has to say. I appreciate the help and will make a diagnostics thread for the community to help future owners. This seems to be a common set of overlapping issues.