Haha.. the image I linked to above is of a non-automatic resettable breaker, it was as your picture - don't know what happened there! Gotta love the internets!
More often than not, auto-resetting breakers on high amperage connection points are generally not used, and instead the breaker type that I pictured above. It certainly sounds like that breaker was your problem - once replaced you should be good to go.
P.S. Gemini5362 - yes indeed DC clamp on ammeters exist, I have a Fluke 325 just for this purpose ;-)
94-Newmar Kountry Star 40-KSDP
Spartan/Cummins 8.3C-300HP/Allison 3060 WTEC-II/25yr RV Tech RVIA Certified/Onan-Cummins Certified