On the first defective one, using the scroll wheel is no good. It will still show movement on the wheel maybe 5% of the time. I have replaced the Kailh encoder, but the issue persists. The second mouse will not charge the battery. When you initially plug in a source of power, it will draw 2.5 watts for about a second and then stops. This current does dump to the battery. Charging the battery with another mouse works fine, it will use up the battery charge and then back to being a wired mouse.
