Changing the battery of a wireless mouse is very easy. All you need to do is buy a fresh battery and replace the dead one. You may use the over-the-counter batteries but I prefer the rechargeable type because it lasts longer and you can just recharge it after its energy is depleted. After replacing the batteries, press the connect button on your mouse. It is usually located under the mouse so that it wouldn’t be pressed accidentally. You need to do this to establish communication with the transceiver connected to your CPU. This is the last step. You can now use your cordless mouse.