I don't know the e83 platform that well but if you had to reset the clock, windows, trip counters etc. then it sounds like a full battery disconnect event.

If you are sure the battery terminals are good then maybe the BST is suspect...? Or one of the links/fuses in the terminal box near the battery?

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Wayne
2005 BMW X5 3.0d (b 02/05)
2001 BMW F650GS Dakar (b 06/01)