Solution: Just refill the water tank with water (no descaling solution) all the way to the "Max Line". Then run the full descaling program again --takes approx. 20 minutes. After the program runs completely you will get the yellow "standby" light on and the red "descaling" light will be off.

Next time you descale, be sure and fill your water tank to the "Max Line" before running the descaling program.
Hint: An incomplete cycle (not full tank) is what makes the red light stay on. In other words, it's staying red to tell you to run a full cycle (beginning with the water tank filled to the "Max Line"). Hope this tip is helpful!