Good luck but my 07 X5 4.8 stayed 8 weeks in the shop over several vists for this. The dealer when stuck has to do the steps that BMW wants them to take and they are very slow. Mine was just waking up and drawing too much current. It does wake up every 70 minutes or so to check on itself.

BMW ended up taking my car back but it took pressure in the form of a lawyer and writing to Munich. That said my 2010 X5 3.5D has been flawless for 4 months now and it was at no cost to me.

I think they concluded it was a battery computer module on my old X5 but they always replace the cheapest parts first. I was on my third battery.