You can prove the converter by plugging it into a known good 120v receptacle, by extension cord.
You need 120 to the converter's receptacle , now dead. Breakers are good (it seems--they can be tricky) Leaves a popped GFI on the same circuit as the converter's receptacle.
you should "only" have 120 to run things in the Rv. Perhaps you have lost one leg of your 50amp and the converter is on that lost leg? what else does not work that might identify which leg it is on?
Now you need to get both legs working. Do you have an inverter pass through 30a on one of the legs that may have quit?