Met some folks in Key West that had left the dealer with a similar issue. New owners were told by dealer refrig doesn't work well without electric.
Thanks to this web site I knew where the GFCI was for the refrig.
Not sure where it is on the 378 (really like the unit by the way) but it will probably be on the passenger side of your unit behind a removeable hidy hole screw out cover. Get a flashlight and look inside, find the receptacle that the refrig plugs into and push the reset button.
I did this on the new unit and bingo, bango, bongo - refrig turned on. The owners thought it was magic - I told them - nope FROGs helping other FROGs - join and be amazed.
US Army - Retired and loving it with our Georgetown 351DS and now our Thor Challenger 37TB.