1. Turn your Toshiba A40-S161 laptop over.
2. Find the laptop battery release button lock for your Toshiba A40-S161 laptop.
3. Now that your Toshiba A40-S161 laptop battery is unlocked, find the battery release button down.
4. Holding the laptop battery release button, gently pull your battery away from the laptop.
5. Now that your Toshiba A40-S161 battery is removed, grab your replacement Toshiba A40-S161 battery for installation.
6. Insert the battery into the slot. Push the Toshiba A40-S161 battery towards the laptop and secure it in place.