Ron's advice is solid. By confirming all breakers and fuses in the power panel are good, you've ruled out perhaps the most common failure points, since the converter receives it's 120-volt input through one of the breakers, and the "reverse-battery protection fuses" for the converter output are in the regular DC fuse line-up in some Parallax units, and separate in others, (I assume you have the Parallax in your 2015 model). Given all breakers/fuses good, and the functioning battery charge from the engine alternator, sounds likely that you've properly diagnosed a bad converter.
Even so, it's always best to eliminate all outside possibilities. If you can verify a good 120-volts right at the converter input connection, and then no DC output voltage right at the converter output connections, you have isolated your problem to the converter itself at just about a 100% level. Note that you will need to pull the two DC fuses providing "reverse battery protection" when checking for DC output voltage at the converter output connection.