Ok, FIrst the battery disconnect is not in the disconnected position.
How do I know this:
"I put the jumper cables to the battery from the truck and everything works"
Converter may be non-working.. Battery may be "Flat" (unable to take a charge)
Adapter to house power may be. iffy.
Now as for the "Everything works with jumper cables on battery"
Trailers have two power systems (motor homes have a 3rd but we will ignore that for the most part) some have an additional power system (Both MH and Trailers) I will cover that.
The first system is the 12 volt system.. This runs all the Lights, Fans, Water pump, Furnace, Slides, steps if they are electric, Jacks if they are electric, it also provides CONTROL power for the Fridge, Water heater and optionally air conditioners (if wall mounted T-stat for sure it provides).
120 volt system Air Conditioner, Operational power for water heater, Fridge (on electric in both cases) and the converter (charges battery provides 12 v when on shore power) appearances are this is NOT working more on that later.
MH only. 12 volt chassis system.. or in your case the battery in your Truck.
optional inverter.. This is a device that makes 120 volt out of 12 volt (the "inverse" of what the Converter does) This may run the microwave and it may need 12 volt battery power to operate the internal control comnputer as well.
So Here are some testing methods.. DO you have TWO A/Cs.. If so turn both to FAN only Do both work when plugged into the house or does just one work.
IF only one.. your problem is the adapter. get a new one (Hey I've seen em happen)
IF both work check all the 120 volt breakers is there one marked CONV or Converter.. That's the prime suspect Cycle it off and on.
The converter has fuses.. they may be blown They are called Reverse Polarity fuses for good reason You will need to find the converter UNLESS it is part of the power distribution panel.. if so look for 30 amp fuses (often far right) if more than one both may be blown and need to be replaced at the same time UNPLUGGED
Finally I have found many RVers have a few screws loose... A #2 Square bit often works well to tighten them.. Start by UNPLUGING and taking a flashlight into the RV and then check each and every screw in the breaker box.
(You thought perhaps my Screws loose was a different type of screw.. nope. Head properly attached. It is the "Oh I would never RV" folks that have that issue :))
Good luck and PLEASE let us know what you find.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times