the lock and the cylinder are two different mechanism.
this is the cylinder (part 15):
Porsche Boxster Door Handle Parts
this is the lock it self (part 14):
Porsche Boxster Door In White Parts
if you look at part 15, you will see a shaft coming out of it.
maybe that's the broken part.
this way or the other, take off the door cover and have a look.
your lock mechanism is definitely good, if you can lock and unlock by using the button.