Active top not opening

I have never tried it, but I think it's possible to use the blue pull rings in the boot to disengage some of the mechanism. Maybe then you could put the roof up and down manually to see if you can feel it it feels tight in one direction.
Other than that, I guess it could be a pump, valve or cylinder sealing problem.
That's not much help I know, but it's unknown territory to me.

 

A note of caution. Section I5-13 of the (dealer) operations manual states:

"The manual operation of the roof is for the roof closing direction only".

The owner's manual gives detailed instructions for how to close the roof manually - but it's a pretty complicated procedure. The owner's manual can be downloaded from this site under "Resources".