The motor drives cables with squared off ends that spin to drive the transmissions. The cables could be broken, or the big plastic gears in the transmissions could be cracked. Pop the ball end sockets that attach to the top, to get the top open enough to get a look.
There's some detail of the parts here: Porsche Boxster Convertible Top Repair - 986 / 987 (1997-08) - Pelican Parts Technical Article
how do i get the CLAMSHELL to open manually .......