Small Engine Troubleshooting Problems? Ask a Mechanic Now.
What engine do you have? Do you have spark if you remove spark plug and ground it when cranking? If no spark, You may have ruined the coil if it had polarity reversed.
The solid state ignition is most likely no longer creating the spark! It does not tolerate reverse polarity. That would be my thought as to what is not working, giving you the no start.