Unfortunately, this model has had quite a few problems, because it is such a complicated refrigerator. Many times a shorted component that is connected to the Iceland main control board will affect completely unrelated items making it easy to chase your tail for hours. I would suspect the freezer thermostor - only because we have had to replace it many times in the past.
Suggest you go to the www.searspartsdirect.com
and copy the electrical diagram and then verify electrical reading on the main PCB, to try to isolate the problem.