As I am not sure which buttons you have I am sending instructions for all samsung units on how to get it out of demo mode. Use the one for the buttons you have and it should go back to cooling.
Here are options to get Samsung refrigerator out of demo mode:
-- Press and hold the 'HOME' and 'HELP' key at the same time for 5 seconds.
-- Open the refrigerator door and then press and hold the 'ICE PLUS/ULTRA ICE' and 'REFRIGERATOR TEMP' key at the same time for 5 seconds. The door should be open.
-- Press and hold the 'ICE PLUS/ULTRA ICE' key and the 'UP/DOWN' keys for 5 seconds.
-- Press and hold the 'EXPRESS FREEZE' and the 'REFRIGERATOR TEMPERATURE CONTROL' key at the same time for 5 seconds.
--Press lighting and freezer for 5 seconds.
--Press power freeze and freezer for 8 seconds
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