Welcome to the forum. I am not familiar with your coach specifically, but I can tell you that the use/store latching relay is shown clearly in your bottom picture (and less so in the upper picture) of your post.
If you are not getting 12vdc from the coach batteries through to the DC fuse panel (which is also tied to output of the converter), then it is possible that the batteries are dead; the use/store latching relay is not closed (not operated to on); the 50 amp mini breaker is tripped open; or there is a bad connection at any of the wiring connections of these mentioned devices to the DC fuse panel. If you can trace the 12vdc output cable from the converter it should go to either the latching relay or the mini breaker first. Your pictures show the latch relay at the back of the converter......but carefully trace the 12vdc power cable as far as you can and with luck the mini breaker will be in series feeding your coach batteries.......somewhere in that series circuit.
The mini breaker can be located anywhere.....near the converter output/DC fuse panel; near the latching relay; or near the coach batteries. In my coach it is located in the BCC (battery control cabinet) mounted in the engine bay of all places. Sometimes a call to Thor tech support will get you to the location.....but that assumes the assembly line worker put it in some “standard” location. Every same model/year coach seems to be built with “variations” at the discretion of the workers. Perhaps someone with your specific coach and breaker location info will reply.
In the mean time a couple pictures that show a “generic” schematic of the DC battery charge circuits (right side is your latching relay and 50 amp mini breaker (they can be order reversed). Another picture shows the mini breaker located close to the output of the converter (black arrow in picture) under the bed in someone else’s coach. The mini breakers are physically not very big and the reset button on the breaker is very small as well. Good luck.
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