Diagnosis
The Light Ring (RGB) on the rear of the monitor is in its default or a previously set lighting mode. It is controlled separately from the front power indicator.
How to Fix It
Press the joystick to open the OSD. Navigate to the 'Lighting' menu (icon resembles a light bulb). Select 'Light Ring'. Set 'Mode' to 'Off'. Press the joystick to confirm. Exit the OSD. The ring will now be disabled.
If That Didn't Work
The setting may not have been saved. Ensure you exit the OSD completely by pressing the joystick back to the main level until the menu disappears. Alternatively, perform a factory reset via System > Reset, but this will erase all other picture settings.
Heads Up
The Light Ring has separate modes: Static, Breathing, and Audio Sync. If you set it to 'Audio Sync', it will react to system sound from the monitor's speakers or line-in, which can cause it to appear active even when set to a static color.