[LOLWOWJason]

Exit and Menu buttons did not work for my 830, Day or night they are always on light...i dont know if there are some problem at software or hardware.
Maybe it was I broke because it recently fell to the ground 3 times....disappointment to nokia...

[RumoredNow]

There is a known issue with the sensitivity (or lack of) on the capacitive nav buttons on 830. The workaround is not to have a screen protector over that area.

As for the light; do you mean it does not follow the autobrightness of the screen or it does not ever shut off even when the phone is put in sleep?

If the former, make sure your Phone is up to date. In Settings > brightness check that screen autobright is engaged. In Settings > display > check your Brightness Profile. Try a Soft Reset.

Lastly, if you dropped your phone 3 times recently, that may be an issue and there may be a connector that needs to be reseated. You could check with a qualified repair shop.