Your fridge is not sensing 120V power - either at the control board, or further upstream. Check for 120V power starting where the fridge is plugged in. If no 120V, keep working your way upstream to find the cause.
If there is 120V at the plug, try resetting the fridge by turning off, leave off for at least 10 sec, then start it back up. If the fridge won't reset, you either have a problem in the control board, or the 120V heater element.