I received mine yesterday (I bought two)

The first one worked perfectly right out of the box.. no problems.

The second one took some tweaking... It did not work out of the box like the first.
The instructions aren't great. "Hold the round button down for five seconds"
There are TWO round buttons - both a little difficult to see and press. One on the mouse (small and recessed) and one on the hub. Both seem to work as a reset.
I must have done a dozen versions of turning on the mouse - holding buttons and fiddling with the battery and switching parts with the other working mouse/base. All with no joy.
The Micro Innovations Web Site was no help.
Finally I got it to work.
It appears that the trick was holding down the button on the base/hub until the LED on the base started flashing quickly. At the same time I was holding the button on the mouse until it started flashing quickly.. then Whoopee -both mice now work!