Tailgate That Only Moves Upward
 

Following broad-spectrum control module replacement (but also prior to that), my tailgate won't move downward under its own power. The driver's side interior button and exterior tailgate button both successfully command the door up - and I've managed to get INPA to send the door up via software commands, too. But other than droop that takes place over a few days of waiting, I can't seem to get the door to move downward.

Any ideas? Could this be a sensor/calibration problem?

I've checked through the threads, but I haven't found anything that details this conclusively.

Any help would be appreciated - this is the last thing I need to figure out before I can get the car out of the garage!

Edit: this is on a 2008 MT 535xi (e61)

Do I get yelled at if I link to another site? Hope not.

Tony has the same problem that I do, for context: https://www.justanswer.com/uk-car/1g...-will-not.html