I don't know Jack, but maybe something here will "spark" an idea! :
Do you have a battery Disconnect switch? If yes, it might be disconnected.
Fuse may also be blown.
There may be a "Main" fuse at or near the tongue.
There should be a fuse in your converter box panel
Try running your lights while the trailer is unplugged to see if you have battery power that is needed to spark the refer.
See if the heater will come on to see if you have gas and spark at it.
Also, if the fan runs while the trailer is unplugged, you do have battery power.
Sounds silly but make sure your gas is on and that you do have gas in your bottle.
Turn on a gas burner at the stove to purge the air out of the lines faster.
This will help purge the air out for the refer too.
Hope this helps!