Primary cause of converter failure... OLD AGE. Seriously they get old and die just like people only a whole lot faster.
Secondary is lung failure.. Ok, failure of the fan that cools the electronics, Heat is the enemy of most electronics after a point and the fan's job is to keep it BELOW that point.. if the fan fails (due to age the device soon follows. And then we have dust build up..
and as some have posted... some converters were bad the day they came off the line.. but if your RV was made This Century.. Odds are you don't have one of those.
After 12 years and change I had to repaace mine
BUT.. There may be good news.
Oh, one more no-cost option... I have tripped the circuit breaker that FEEDS the converter... I have also had several loose wires (The point where they attach to the power panel, both hot and neutrals) and my converter is a plug in model.. comes unplugged sometimes.
Somewhere on your converter shoudl be 1,2 or 3 fuses, ikely 30 amp. they can also fail (or blow) failure is due to age, blow to current, but the effect is teh same, NO POWER. Mine were in a place where mounted I coudl not see it,,, but They were not blown.
Progressive Dynamics (marshall, MI) if your converter is aqlso your power distribution panel 4600 series repalces the "Guts" if it's a stand alone box 9200.. Same operationally, just a different box. Dongle optional.