By "hooked it up wrong", are you saying that you hooked the negative cable to the positive terminal, and the positive cable to the negative terminal?
Don't you just kick yourself when you do stuff like that? I fried a $600 alternator by hooking up booster cables backwards one dark morning when I was already late for work. (not on the Boxster, fortunately!)
This fella had a similar experience:
Help, Help, Help I think I killed it!!!
I'd say there's a good chance you've toasted something. If troubleshooting electrics isn't your forte (I'm not trying to be funny, really) then you might want to get it in to be checked out before it strands you somewhere inconvenient.