Try to run this from a terminal:
pkexec /usr/lib/gnome-settings-daemon/gsd-backlight-helper --get-max-brightness
This should not return '0' as a result, but a number > 0.
If this command does return '0', your system is not supported, because it uses the gsd-backlight-helper to change display brightness.
Try to run this from a terminal: gnome-settings- daemon/ gsd-backlight- helper --get-max- brightness
pkexec /usr/lib/
This should not return '0' as a result, but a number > 0.
If this command does return '0', your system is not supported, because it uses the gsd-backlight- helper to change display brightness.