Had exactly the same problem in Texas. The friction inside the gears of the motor is to low and at very high temperatures. The motor is deenergized at the correct spot, BUT due to inertia the little driveshaft with the gears continous to turn a little. Just enough to energize the motor again.

My solution: I packed the gears with a lot of high temperature grease. The grease slows the little gears down sufficiently and the problem is gone. Works since 2004...(and here in Spain too)
I even grounded the hatch motor in the trunk directly. I did not like the idea of my fellow german engineers to open the door all the time if I want to release the rear hatch with the pull ****.

 

Cool, that's easy enough to try.