Hi Jake, Thank you for listing a good model# and what you have tried along with what is the issue! It helps us help you a lot!
So no, do not throw this out! It is a good model and should last ya a while longer yet once it is fixed.. On to it
The damper is just a doorway similar to the vents in your home for the heat and cool. You flip the lever up and no air blows through but flip it down and you get the full effect. Close it halfway and you get some but not all. Same principal in your fridge and normally the "freezer" control should be set in the middle for the damper to be half open.
The defrost board is a counter.. Every eight hours that the fridge runs, it will shut down for 30 minutes and turn on the defrost heater as needed. Then "dwell" to allow water to drip off before it turns the fridge back on to cool. This does not control the cooling! It can if it is dead off, or if it stops defrosting.. But not in an "overcool" scenario like what you have.
Lastly you have the thermostat.. Think of it as a switch that works off temperature so it gets cold and turns off, it gets warm and turns on.
The thermostat usually goes bad and it does not run at all but it can go bad and never shut off!
Remember the switch?
Part# is W11088945
how to video here