Moved to Dodge: Neon.
How long did you leave the battery disconnected? Some cars it takes overnight to reset the ecu. I don't know that the Check Engine light would be on just from overheating - usually it means failure of an emissions/fuel system part such as o2 sensor, etc. And what happens now if he needs to honk?? I'd go to a junkyard and get a replacement relay if I were you.