but the freezer is too cold (a thermometer place there went down to the minimum it could read which is -40°F).
Refrigeration parts ( compressor, gas charge ) would seem to be ok then.
The refrigerator is too warm (a thermometer in it says 52°F)
Poor air flow ( bad evaporator fan motor, air damper closed/broken, air return ducts frozen over ), door got left open a little and we got ice where we shouldn't have, light not shutting off in the fresh food section.
What could be the problem and how much to repair? Worth repairing, or should I buy a new one?
I'd unplug it, remove the house fuse, turn off the breaker and leave the doors open for an 24 hour defrosting and then fire the refrigerator back up to see what happens.