The left / right button is unresponsive, or double-clicks / multi-clicks on its own. What should I do?

The left / right button is unresponsive, or double-clicks / multi-clicks on its own. What should I do?

Please test on another computer first to rule out software factors, and update to the latest firmware.
If a button still doesn't respond or registers multiple clicks, it's usually a button micro-switch issue — please apply for repair under warranty.