Your mouse uses an infrared (IR) Laser light that is invisible to the human eye.
If you're not sure whether your mouse is powered on, check the ON/OFF switch located on the bottom. When your mouse is:
ON - The switch is pushed over to the right and you see green next to it.
OFF - The switch is pushed over to the left and you see red next to it.
NOTE: The Marathon Mouse M705 is included in the Wireless Solar Keyboard & Marathon Mouse Combo MK750.