Buttons clicking but not sending a signal usually means there is residue under the metal contact device. The mechanism under the rubber button is really surprisingly simple and resilient. The layout for the circuitry on each button is the same:

1) A solid circular dot shaped copper contact point, 2) A thin concentric copper ring surrounding the center dot.

There is a gap between the center dot and the surrounding ring. This is the electrical switch that is bridged when the button is pressed.

A small metal bulged plate sits on top of the circuit. The outer edges sit on, and make contact with, the outer ring, while the center is bulged upward over the center dot, not making contact (until pressed!).

Typically residue is coating the circuit board and metal device and preventing the electrical signal from bridging the two contact points.

Once the remote is opened, a white sticky film can be pulled back; the metal contacts and circuit board can be cleaned. Ensure the metal piece is oriented correctly before laying the film back down, and all is good!