There was a youtube video by samcrac where he troubleshooted a 2012 M6 with whole bunch of failed electronics. He tracked the root cause to a plugged up sunroof drain that left poodles of water saturating the driver footwell and all the modules that resides in that area.

Once he dried up all the modules and replaced a few broken one, the car was good to go.

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2003 X5 4.6is Estoril Blue, acquired March 2018
2013 128i M Sport 6 MT Space Grey daily driver
2010 535xi 6 MT Barbera Red