Diagnosis
The control board is glitching or has lost power. This often happens after a brief power interruption or a voltage spike.
How to Fix It
Unplug the fridge from the wall outlet for a full 5 minutes. Plug it back in. This performs a hard reset on the digital control system. The display should return to normal.
If That Didn't Work
Check if the unit is in Fahrenheit or Celsius mode. Accidentally holding the temp buttons can switch it. Press and hold the "C/F" or temperature up button for 3-5 seconds to toggle between modes and see if a readable number appears.
Heads Up
Never plug this fridge into a power strip with other high-draw appliances. Use a dedicated wall outlet to prevent voltage fluctuations that can scramble the digital controls.