It turns out...
 

that it was just a bad battery. (Yes, I totally overreact to these things.) So I went and replaced the battery myself.

I need to find a new mechanic possibly. If my local mechanic (who I go to in order to save money by not being taken by the dealer)...tries to get me to spend $1200 + labor for something I could get fixed for $150, then I might as well just be taken by the dealership where i could at least have the peace of mind that everything is guaranteed by Porsche. Do any of you have any opinions on this?