Start with the basics
Check that the refrigerator has power and that the temperature controls have not been changed. Keep the doors closed as much as possible while checking the issue.
Give airflow some space
Move food away from interior vents and check that the door seals close properly. Follow your manufacturer’s instructions for clearance around the appliance.
Know when to call
Persistent warming, leaks, or unusual noises need a professional diagnosis. Do not open electrical panels or attempt sealed-system repairs. If food safety is in doubt, follow current food-safety guidance.