From your description, it sounds like you're talking about a Circuit Breaker (CB) in the tongue? Yours may be one that needs to be manually reset. Is there a button on it that you can push to do this?
If it's truly defective, you can find them online or in automotive departments of stores, they are 30Amp Automotive CBs and you can just look for one that looks like yours. Does it look sort of like this one from Wally World? https://www.walmart.com/ip/BUSSMANN-...-14V/159616508