You should always carry a cheap voltmeter (10 bucks anywhere) and a test light with you at all times. An outlet tester works wonders to make sure your campground is supplying correctly wired power.
How did you "check your fuses" without a ohm meter?
Did you just look at them? Not always reliable.
We may need to go inside the converter to troubleshoot next so if you are not at all handy with electrical items (and your lack of a voltmeter is a red flag) you will NEED to go to the dealer.
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW