Bottom Left Trackpad Button not working

The bottom left click on the trackpad of my Latitude laptop has stopped working. All other parts of the trackpad are functional, including the bottom right click button, the top left click button, the top right click button, and the trackpad itself. There is no water or visible damage (the button is not depressed and audibly makes a click like normal when pressed), so it does not appear to be a hardware issue. 

I have reinstalled all drivers. I have even done a factory reset of the computer and reinstalled Windows. It still does not work. 

What are my options?