On the MX keys, as far as I can tell, the backlighting toggle's only purpose is to manually disable the possibility of the backlit keyboard. I think If the button is blue (turned on), then the backlight should never turn off. I do not understand the purpose of restricting the keyboard from ever lighting up (current function?). I have seen many posts online complaining about not being able to force the keyboard to always keep the backlight on (rather than automatically turn off after 5 seconds). I just want my keyboard backlight to turn on and stay on. Thank you!