Nice, real complicated's. My 2001 has fakes. You tried to push the leaf forward with your finger or a screwdriver with it plugged in and it didn't work?
You can open the case, plug it in, and try to use a wire, or clips or something conductive to connect the offending switch terminals underneath the board to try to see if it really is the switch or something to do with the chip or matrix. Or better if you have a multimeter with a continuity meter you can just use that to see if the switch is closing.
If you have extra switches of course, it's fairly simple to desolder it and replace it once you get it open.
It's likely it is the switch, the parts do get bent out of shape after thousands of keypresses. I just had a complicated switch go dead on me out of nowhere on one of my modified siigs that I just did a few months ago. You can usually get it to work again though without a major operation by taking off the actuation leaf, and putting a little more bend in it, so there's just enough room so that you can just get the key spring back in place.