my ninja dualbrew pro says 'CLn' on the display and won't brew, what do I do?

The CLn message means heavy calcium scale has blocked the heater. The machine is locked out until you run a full descaling clean cycle.

1. Empty the carafe and place it under the brew basket.
2. Fill the water reservoir to the Travel Mug line (16 oz) with white vinegar. Fill the rest with water up to the Full line. Do not use anything but white vinegar.
3. Press the CLEAN button, then press START BREW. The cycle runs for about 75 minutes.
4. When it ends, it will beep and display "End." Empty the carafe and clean it and the brew basket thoroughly.
5. Run a water-only cycle on the mode you cleaned to flush any remaining solution. If taste persists, run another water cycle.

If you cancel the clean cycle, the brewer won't be descaled. You must restart from step 1. Hard water causes this faster; run clean cycles more often if you have it.