mine seemed to work after I shut it down and restarted as well.
The test is easy, unplug the thermistor, place a cup of water on the top shelf, near the cooling fins, leave in for 24 hours. Check the temperature, if it is below 40 degrees, then the cooling unit is working properly, and is not the issue. I did the test and I was at 36 degrees. When u take the thermistor out if the equation, the fridge just constantly cools, nothing to tell it to kick on and off so to speak. If this test fails, and the liquid is about 40, then the cooling unit is bad. This is what the RV tech told me, he was very knowledgeable. He is a Norcold tech. If the test is good, 90% of the time it is the thermistor. I got it on Amazon, here is the link..
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1