The LED beside the power button is a status light to show Wacom Cintiq Pro 27 statuses such as Sleep mode, Power on/off, and Pen/Touch status.
Display ON
LED ON (Color: Blue)
*After 5 seconds, LED turns darker
(Brightness change from 100% to 50%)
Display Standby/Sleep
LED Breathing (Color: Amber / maximum brightness: 50%) *1
Display OFF
LED OFF
Pen input active
ON (Color: White) LED Brightness 50%
Pen input de-active
LED OFF