Re: reverse polarity
Sounds like you are trying to start the car with a battery charger attached. Though I mentioned some posts ago you should never, never, never do that.
Modern car computers really do not like the trash a charger puts out (unless you have a special one, it does not put out DC, its more of a sorta half waver rectified ac component).
Little float chargers are usually OK but nothing over 5 amps. Period. If in doubt, use a jump box.