It seems like you've damaged the Flex oder the Button itself. If youve allready checked the connection to Motherboard, then you need to replace the Daughterboard to solve the issue
I could not find and led cables to remove... and after there repair the led light forsaken the soft keys do not light up but they do work and vibrate... what should I do?
I would definitely recommend heating and prying before carrying out step 17. There is a lot of glue holding the frame together and not heating and prying could easily lead to screen damage.