Your keyboard is rechargeable. There are no batteries to be replaced.
A three-hour charge provides up to 10 days of use when you type about two hours a day with the backlight on, or about one year without the backlight.
NOTE: The use you get between charges may vary depending on your usage pattern.
When you turn on the keyboard, the battery indicator:
Blinks green when the battery is charging
Glows green when the battery is charged
Blinks red to indicate that battery power is low and the keyboard should be recharged
To charge your keyboard’s battery:
Connect the keyboard to a computer using the Micro‑USB charging cable.
The battery indicator blinks green while it’s charging. Charge the keyboard until the indicator light stops blinking. You can use the keyboard while it charges.
NOTE: If the battery power is low (indicator blinking red), the keyboard backlight is disabled.