Is there a special way to start the car after removing the battery? A special anti-theft code? and if so how would one, like myself, find it?

I have an 09 fit sport navi/5 speed.

 

Put the battery back in?

Just need radio code to get it to work,but most likely you blew some fuses. Check them.

 

The radio code was included with my purchase (dealer put it in the car manual's folder).

Your post reminds me of way back when I had my first car and the installation of subs/amps caused things like this...lots of headaches basically.