having read the myriad of threads about setting the backlight at boot, I decided to try the xbacklight method. works fine running from the terminal with the command:
"xbacklight -set 50", for example, so I put this as a startup command so it would be executed at boot. While booting I witness the screen dimming accordingly to 50%, but then the screen goes back to 100% brightness prior to the desktop appearing.
Using LM 13