If there is no power, there's a good chance you just damaged the battery and not the car. Check the volts on the battery with a multimeter, it should be over 12 volts at least. Fully charged battery has 12.6 volts. If the battery is bad, get a healthy battery, but keep an eye out for any smoke from the interior/fuse box when connecting the battery. You may have melted components causing a short, and applying power to the vehicle if there is a short can result in fire.
In worse case scenario: you could have fried the control modules / computers / sensors in the car if not the entire ecu, you may have to pull the dash and inspect all the control modules for damage. This will likely be a pretty expensive fix.