Jumped car off rear 12V.....how bad is it??

UPDATE: I installed the new 12v battery this evening and everything seems to be back to normal. Of course I had to redo the stereo and re-disable the seat belt and backup beepers but other than that it's back to no warning lights and driving fine (as fine as a 2005 prius is expected to drive, that is).

Thank you everyone for the suggestions and information. And for anyone reading this thread later.....jumper/charging directly off the 12v battery won't "BRICK" your car and cost thousands of $$$. Just make sure you get the polarity correct.