Hello, and welcome to the forums. I'm guessing you've reset the 12-volt breaker at the panel? If so, and the wire is burned looking, then it appears a short to ground has developed somewhere along that circuit. If there is indeed a short present, resetting the breaker probably won't be possible, as it will just trip again. However, if you are able to reset, or was not tripped to begin with, your problem is likely a failure at the converter - which would be unusual with a fairly new trailer, but not out of the realm of possibility.
What other problems are you having? You've come to the right place for help!