Have the battery fully charged and tested. Get several opinions if not conclusive, it could be a number of problems, but starting with the battery and then testing other components is a good way to start troubleshooting.
2001 BMW E38/750il V12
Anthracite Metallic: If this car were any faster, I would have arrived yesterday!!
BMW, the ONLY driving machine.! By the way, yes, it's fast...and NO! You can't drive it!! Power, elegance, styling, technology that is still cutting edge, the ultimate driving machine for sure.!