DIAGNOSIS The machine has hit its programmed cleaning reminder (usually after 24-48 hours of cumulative use). It won't operate until you run the cleaning cycle.
FIX You need to complete the cleaning cycle. 1) Ensure the ice basket is empty. 2) Fill the water reservoir with a mixture of warm water and about a cup of white vinegar (or a descaling solution). Do NOT use harsh chemicals or soap. 3) Press and hold the 'Clean' button for 3 seconds until you hear a beep. The cycle will run for about 10-15 minutes, pumping the solution through the system. 4) When it's done, discard the water, rinse the reservoir thoroughly with fresh water, refill it with clean cold water, and run one or two ice-making cycles to rinse out any remaining vinegar taste.
IF THAT DIDN'T WORK If the clean light is still flashing after completing the cycle, the machine might not have registered it. Try unplugging the unit for 30 seconds, then plugging it back in. This often clears the reminder.
HEADS UP Never skip the rinse cycles after cleaning. Vinegar left in the lines will make your next several batches of ice taste sour.