Reset of control board is ONLY needed if you get a 'No Co' error and 'lockout'
Which means neither electric OR propane would work.
(RV Tech would know that vs some repairman looking to justify his service call)
What model is this Norcold.
AC Mode requires 12VDC for controls
AC Mode is 120VAC from a working outlet to control board via the power cord
Then the 120VAC goes thru the GLASS Fuse (typically 5A but can be 8A if 2 elements are used)
Then from Fuse `120VAC goes to the element (if 2 elements both have to work)
SO which Model??