I have an 2007 bmw X3, the car has 90000 miles, electric windows, door mirrors, and mirror retractors.

This is my second right front regular change. The first one went off with out a hitch.
This time I am having a weird problem. Before the swap the left side unit worked great. But after the regular change nothing in the left side control unit works.
During the regular change I disconnected both terminals. And after I discovered that the unit was not working I checked the fuse block and disconnected the ground for 2 minutes. But nothing.

Any ideas on what happened?