So I'm having an issue with the LED backlight -- not a single LED, I mean the entire backlight. The FN key and the windows lock key (f12) light up when they are supposed to, but the function keys that are supposed to toggle on and off the rest of the backlight no longer do so (f1-f4 keys). Yet the f1-f4 keys clearly work, for instance, pressing f1 brings up the Chrome help menu, as intended. Any idea whether this is fixable, or how? I assume there is some circuit that controls the toggling on/off of the backlight for most of the keys, so maybe an issue with that?

Thanks for any suggestions.