While running (or more specifically loading ubuntu 16.04) ubuntu sets my keyboard backlight to off (brightness, not on/off, but lowest possible brightness). I setup Windows 7 (since it actually has driver support from dell), and was able to crank back up the brightness. When rebooting into linux, keyboard backlighting goes away again. This has not occurred in Debian Testing (Stretch) nor Linux Mint 17.3 (14.04 based). Additionally I do not recall the issue occurring in Gnome-Ubuntu 15.10 or 14.04.
Random googling brought me to "xset led 3" but I am pretty sure that did nothing 😀