An important note about having SOME skill to repair MANY things that you haven't achieved expertise in:
Always know, and be willing to admit, when a problem has reached the end of your knowledge and it's time to call an expert.
My attempts to repair the fridge reached that point, having ruled out sensors, and cleaning, and fans, etc. My portion of this mission is complete. I feel satisfied I gave it my all, and have ruled out everything I'd be able to fix. And I've done so without new damage.