Welcome and thank you for allowing me to assist you! Yes you probably did fry the radio, and I am afraid you will need to replace it. I have seen issues with a poor ground at the antenna base where it mounts to the fender. So when you get the radio replaced, remove the antenna base and scrape off some paint on the inside of the fender where the base contacts the fender. This will improve the ground connection and help with AM reception.
I hope this information helps, and let me know if you need further assistance with this.