The most obvious thing is the disable switch has been activated by moving the shelf in the trunk. If the shelf is moved up (large boxes in the trunk perhaps?) the the top automatically disables the top lowering so you don't "crush" the pocket with the top. Sometime the switch just goes bad or the shelf goes out of alignment. I would move the shelf up and down and see if it's locking into the center slot.
Other than that there are a series of safety items that prevent the top from going. Make sure things are secure. You can manually open the top by enguaging the release in the trunk and lifting or closing.... might be good to get things going.
Typically when the top releases to open, but does not move and red light flashes means the motor is dead.
Try searching the you will find lots more information.