Refrigerator not cooling, bottom freezer over freezing and frosty

Whirlpool Model GB2SHDXTS02 / S/N KY1331093

Refrigerator section does not cool but bottom freezer is cooling and making ice but is freezing up. I have replaced the capacitor, the control (jazz) board, and most recently, the damper assembly control. The damper was damaged but that was not the issue apparently! I am at a loss. I am pretty sure the evaporator fan/motor is working (pretty sure) but I am aware that it could also be the thermistor or the bimetal defroster. We have a borrowed fridge that has its own problems and won't last much longer! Please help!

It sounds like a defrost problem to me. Have you checked the defrost heater or defrost bi-metal?

Parts 10 and 14 on this part diagram.
http://www.appliancepartspros.com/unit-parts-for-whirlpool-gb2shdxts02.html

If the freezer coils are full of frost, that would prevent cold air from being blown into the fresh food section.

I haven’t checked those specifically. As much as I have found out about my fridge I don’t know all! Do I need to check it unplugged and defrosted? This would seem to defeat the purpose. And getting into that section of the freezer looks daunting as I can find no diagrams or schematics to access that area with out breaking anything. Could you give me s basic step by step or refer me to something that can? I supe appreciate it and am pretty much ready to take it out to a field and put it down Office Space style. While not logical it would be immensely satisfying! Thanks again and look forward to hearing back from you!

Watch these videos and see if they look like your refrig.

https://www.youtube.com/watch?v=yOHr1WWJvT0

http://fast.wistia.net/embed/iframe/37mzqgxgj0?controlsVisibleOnLoad=true&version=v1&videoHeight=240&videoWidth=330&volumeControl=true&autoPlay=true

To check the bi-metal also known as a defrost termination thermostat, it has to be frozen. The element can be tested warm or cold.

The first video does look like mine, without the French doors. The second, not so much. My husband has a multimeter so I will check both and get back to you. I need to check the heater element and the bimetal defrost thingy. What about the thermistor? What ranges am I looking for? Thanks again for the help!