20*F in freezer is NOT fine...........S/B 5*F or lower
Cooling unit is most likely clogged..........dying........dead!
OR DOOR seals are no good allowing warm air int freezer section
What temp setting is fridge set to (5 or 9)??
When you push 'temp' button.....does it Flash for 10 seconds?
If it does 'thermistor' is bad.
No flashing when you push 'temp' button......
Select 9 on temp setting
Unplug thermistor at lamp assembly
Check temps in freezer/food section again after 12 hrs.
No improvement (freezer 5*F or less/food section below 40*F)
Cooling unit bad!