On some laptops, screen brightness gets stuck at maximum and the function keys or desktop settings don’t seem to do anything.
There is one thing to try that usually fixes this. Open /etc/default/grub and find the line starting with GRUB_CMDLINE_LINUX. Append acpi_backlight=vendor to this line so that it looks like this:
GRUB_CMDLINE_LINUX="... rhgb quiet acpi_backlight=vendor"
You then need to update the GRUB2 configuration file. This is usually located at /boot/grub2/grub.cfg. On UEFI-enabled systems, it’s probably located at /boot/efi/EFI/fedora/grub.cfg. If you’re not sure where it is on your system, there’s usually a symlink to it from within the /etc directory. Run the following command with the correct location:
# grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
If you’re using Linux kernel 3.13 or later, you can try this instead:
GRUB_CMDLINE_LINUX="... rhgb quiet video.use_native_backlight=1"