What Does This Error Mean?

A Nook backlight that does not turn on is usually set to 0% brightness or is toggled off in the display settings. Swipe down from the top of the screen and drag the brightness slider up. If the slider is at maximum and no light appears, a soft reset usually restores the GlowLight function.

Affected Models

Nook GlowLight 3
Nook GlowLight Plus
Nook GlowLight Plus E-Ink

Common Causes

Brightness set to 0% in the quick settings or display settings
GlowLight toggle switched off in the settings menu
Software glitch preventing the backlight driver from responding
Nook in power-saving mode suppressing the backlight
Hardware backlight failure (less common — usually affects older devices)

How to Fix It

Check the brightness slider.

Swipe down from the top of the Nook screen to open the Quick Settings panel. Locate the brightness slider and drag it to the right to increase brightness. If it is already at maximum and no light is visible in a dark room, proceed to the next step.
Toggle the GlowLight off and on.

In the Quick Settings panel, find the GlowLight toggle. Turn it off, wait 5 seconds, then turn it back on. This forces the backlight driver to reinitialise, which clears software-related backlight failures.
Restart the Nook.

Hold the power button for 20 seconds and release. Wait for the Nook to fully power off, then press the power button briefly to restart. A soft restart often resolves firmware states that lock out the backlight control.
Check power-saving settings.

Go to Settings > Device > Power. If Battery Saver or a similar mode is active, it may be suppressing the backlight to extend battery life. Disable power-saving mode temporarily and test the backlight again.
Factory reset as a last resort.

Go to Settings > Device Info > Erase & Deregister Device. A factory reset wipes all content but can fix deep software faults that survive a restart. Back up any sideloaded content to a computer before resetting, as it cannot be recovered.

When to Call a Professional

If the backlight remains completely off after a factory reset and brightness is confirmed at 100%, the LED backlight strip has likely failed and the device needs hardware repair.