The cursor drifts off the screen.

Generally speaking you should not have problems with the cursor drifting since the mouse was calibrated prior to shipping. Turn the mouse off then on, to reset the device. Double click the Gyro activation button (this will keep the gyro on).
Set the mouse on a steady surface (table top). Since this is a mouse you will have to set it on its side or with the front of the mouse hanging over the edge, otherwise the desktop sensor will automatically activate and stop the Gyro function.
The cursor will start to drift but should stop within 7 to 10 seconds as the Gyro re calibrates.