Auxiliary Breaker Location
The auxiliary breakers for your RV are located in the wire connection section of your battery box (bottom picture that you posted). They are located in the bottom of that picture. You will see a large red wire connecting on the left of the picture which provides power to the breaker buss bar. The breakers are located under this buss bar with the studs facing out. In your case, you have 3 breakers: the one on the left has a black wire attached, the middle one has a green wire and the right one a red wire. The breaker that concerns me is the one in the middle (the one with the green wire) which does not have a nut on the stud to connect it to the buss bar. This may well be your problem but even if it isn't you need to replace the nut on this stud and snug it down. Most likely your RV has auto-reset breakers which do not have reset buttons, but reset themselves after a period of time.
After you replace the nut mentioned above, use a test light or a voltmeter to ensure that you have 12V on the wire side of each of the three breakers.