Here is what you need to do for TEST of Cooling Unit
Unplug the electric heater element leads from the lower circuit bd.
Check that BOTH elements are good.....64 ohms each
Plug the leads DIRECTLY into the 120V AC Outlet (unplug fridge power cord and plug the leads into the outlet)---4 leads. 2 Black & 2 Yellow
Connect the 2 blacks together and the 2 yellows together....1 set of black into one of the slots on the 120V AC Outlet & 1 set of yellow into other slot on the 120V AC Outlet
Turn fridge ON---and let it run at least 12 hrs
Then measure temps in freezer/food compartment
Freezer should be 10*F or lower and Food compartment should be 40*F or lower IF cooling unit is functioning
If NOT....cooling unit is NOT capable of cooling and will need replaced
IF it does cool down then you have an issue with circuit bd, thermistor,