Norcold fridge error

Off the top , Its not the entire fridge.
Its a tuff call without using an rv tech, to avoid throwing parts in it .

There is a solenoid on the gas valve, they can go bad .
Could be a heater element going bad or circuit board.
I replace all my cheap OEM boards with U.S. made Dinosaur boards. Youtube shows you how.
Using good boards has cured most all of my appliance issues.
If you have access to a mobile rv tech in your area, it might be worth a call.

A Dino board today is $250-300. For the part.

You could try these guys. I think one of them is or used to be "TheNorcoldGuy" operating out of Michigan, but this website suggests Florida.
Ask them about it. I used The Norcold Guy a few years back for some replacement parts and they were very helpful and quick to respond.
https://rvfridgeguys.com/

Here is a Manual
See 19 7 20 for wiring diagrams.
Good chance the element is bad.
Have you checked the fuses on the control board.
Most people do not operate refer on 12-volt DC.
Operate on propane or 120-volts.

Here is element info.

https://www.irv2.com/forums/f115/changing-norcold-refrigerator-heater-element-212420.html