Not sure what the top photo is. If it's a breaker try cycling and resetting it.
The bottom photo is the breaker common on many if not all campers. Test it:
1. Disconnect shore power. Check the circuit breaker in the bottom photo by checking for 12vDC between both screws and ground (the trailer frame). This will determine if power is getting out of the battery to this point and if there's voltage on both pins it's getting thru the breaker. Bad breaker is a simple replacement. You can also bypass this breaker with a wire jumper if you have to while waiting for a new part. At your risk, of course.
2. If the breaker is good: Disconnect the battery (remove all wires from the negative pole) and reconnect shorepower and repeat the tests. This will determine if the wiring between the breaker and the converter (which we know is good) are connected to each other. If not the problem is in the wiring between this breaker and the converter.
#1 is more likely than #2 based on the fact you fried the reverse polarity fuses in the converter which can't happen if the battery and converter ain't connected. No point in chasing your tail if this breaker won't reset. If this is good the tail chasing may resume.
The reverse polarity fuses are good as Chickdoe notes.
-- Chuck