@Mom in NY Unfortunately, this is an ongoing issue with Keurig coffeemakers. I have the Supreme Plus model and the same thing. Even after 3 or 4 full containers of water (72 oz) in each flushing through the coffeemaker, the light refused to shut off. I tried so many things to get rid of it and, honestly, I don't know which one worked after reading so many tried options online, but suddenly the descale light was gone.
Having said that, it's been about 3 months since that happened and, wouldn't you know it, the Descale light is on for a new descale. How is it that something like this puts one into a mini anxiety over it? I need to tend to it, but have been procrastinating.
Cinderella is proof that a new pair of shoes can change your life!