How many miles were on your fluid? Chances are a software upgrade from the dealer would have cured the problem. At this point, I would drop the pan and save the fluid. Change your filter, screen the fluid you drained and put it back in the transmission and top off as needed. Then get your software updated and leave it alone after that. I have over 314,000 miles on the original fluid with updated software and absolutely no shifting or other operational issues with the GM transmission.

2002 X5 3.0 314,500 miles
2014 428i 24,300 miles

2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles

1970 Firebird - Under restoration.