Chosen Solution
Keyboard backlight hasn’t been working for a while - tried resetting etc. Where is / which is cable to check to make sure it is plugged in? May have happened when battery was replaced. Can’t seem to find the answer for this mac for this cable. Thanks.
The keyboard backlight connector can be seen in this IFIXIT guide: MacBook Pro 15" Unibody 2.53 GHz Mid 2009 Logic Board Replacement Jump down to Step22
