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Try this -
Check to be sure the gaskets are sealing on the doors.
Check to be sure that the lights inside turn off when the doors are closed. They should turn off 1/2" before the door closes.
Go into the freezer and check the back wall. Do you see frost on the back wall? This points to a problem with the defrost system.
If you want to check a defrost issue further and get the unit running (temporarily), you can remove the food and manually defrost the entire unit.
You can manually defrost the refrigerator by unplugging it and opening the doors. You can speed it up with a fan and/or carefully use a hair dryer to melt frost. The unit will take 12 to 24 hours to reach room temperature. Afterwards, you would plug it back in.
If the refrigerator works correctly after 24 hours, the problem was likely the defrost system and you will need to troubleshoot further. The problem will return in anywhere from a few days to a couple on months (some extreme cases).
Let me know if you would like more information.