Ok, I performed the repair today. It is now clear the button fails due to fatigue in the rubber that we call the button, only a small portion of the rubber protrudes through the door handle. Second, I would be lying if I didn't say I had a couple moments of panic on whether I would be able to get everything back together....but I did. To those of you willing to give this a try I have some tips that I learned the hard way, this is a 2009 CX-9 GT model and I assume it is similar to other years (my comments are for the drivers door).
First thing to do is roll up the window and tape it securely in the up position.
Remove the outer door panel (2 bolts under the silver trim, a screw behind the inner door handle panel). Search this forum for the manual which has VERY basic instructions but they help. Then you pull out from the bottom until the plastic studs release and then up to release from the top of the door. You'll then need to disconnect the power plugs and slide the inner handle through the opening. All this was very easy and took only a few minutes. Oh, you have to also pop off the inner triangular panel near the door mirror.
This is where is gets interesting. Remove the speaker. On the inner panel remove every bolt that you see, the bolts holding the panel are 10mm and there are a bunch of them. Remove the bolts holding the window motor (3 10mm and longer) and remove 2 10mm nuts (these are holding the window regulator to the panel and this is why you must tape the glass). Disconnect the wiring as necessary, the inner panel will be moved to the side and not completely removed so there is no need to cut through the wiring tie wraps that hold it in place. The inner panel is stuck to the door with adhesive, grip at the bottom and pull until the adhesive releases. Move the panel over to the side out of the way...the wiring is still attached.
Carefully release the glass and lay it inside the door at an angle so that you have working room near the lock mechanism.
The two nuts that hold the door handle on are 10mm. Release the two rods held by plastic retainers. Release the two screws holding on the door handle (kinda tight clearance but doable), note how the wire runs to the door handle for the switch (only because you need to run it outside the window channel or you'll be doing the job all over again). Remove the door handle and replace the switch (2 very small screws).
Reverse the order to put door handle back together. Put the window glass back up and tape in place. The inner panel will now line up with the regulator and you can put the two nuts back on (you can reach your hand through the speaker opening to help line things up. Once you get to this point you are home free, just put everything back the way it was...don't forget the bulb that goes to the light in the door.
Took me about 1.5 hours to do the job, the only thing I did not do correctly was tape the glass, it was about halfway down and when I pulled the inner panel loose the glass fell inside the door (luckily no damage), this is where I had my panic attack. If I did it again I could do it in 45 minutes or less. Sorry, no pictures but hopefully my commentary will help.