did you hear any loud popping sounds when operating the top? if the clamshell is moving it means your transmissions are not busted but probably the plastic balljoints connecting to the top itself have either popped out or are broken. it's common and an easy enough thing to fix if that's the case.
read up to learn more about how to diagnose:
Porsche Boxster Convertible Top Repair - 986 / 987 (1997-08) - Pelican Parts Technical Article
your light most likely came on because the top didnt close all the way down and your microswitches detected that, things maybe went south at that final step when the top and clamshell are pulled down securely just before the light would go off on the dash.