I wonder if editing grub to make it switch to the intel_backlight might help
and make the line that usually looks like this
sudo gedit /etc/default/grub
be this instead
If that doesn't work, you may need to add a file
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video.use_native_backlight=1"
And enter this
sudo gedit /usr/share/X11/xorg.conf.d/20-intel.conf
Option "Backlight" "intel_backlight"