Junction Box

Not sure I understand.

My RV repair man said there is power to it...

I have one outlet by the booth dinette that stopped working.

Try this link to the Winnebago website for wiring diagrams and layout of your RV.

Well if there's power to the outlet but nothing coming out, it either has a bad connection or the outlet is faulty.
It doesn't sound like your repair guy is savvy with electricity.

Check for a GFCI plug. It might need to be reset. Just check the easy things first.

#1 there is 'Nothing' installed in a hidden junction box that can trip !
illegal to put circuit breakers, fuses, or switches in such a location

NOW did your tech say the circuit breakers had power
OR
did he say power at the 'outlet'
if there is power in the out let box, the outlet is bad

yes there could be a broken or loose wire someplace between the circuit breaker and the outlet, yes there probably is a junction box with connections in it

IS your dinette in a slide out ?
then you could have a broken or loose connection somewhere with the flex cord for 110v supplying that outlet

If there is power to it then the suspect list does not include Junction boxes

(Well it might)
The suspect list
Prime: whatever you are plugging in (No longer functional)
secondary: The outlet itself (Rv Outlets are basically junk in my opinion)

TO test
first obtain a volt meter. one of the plug in meters like CW et-al sells or a Kill-a-watt. NOTE I really like the Kill-a-watt about a Kilobuck worth of meters in a 20 dollar box.

Plug it in and see if there is a reading. IF so good
plug in a lamp 100 watt incandascent and now look at the voltage and current readings. Should be 120 volt and just under 1 amp. power factor should be 1.0
This is a good outlet

if the voltage goes way down or even dark.. Bad connection Most likely AT THE OUTLET.