1. Turn your Sony VGN-FW398Y laptop over.
2. Find the laptop battery release button lock for your Sony VGN-FW398Y laptop.
3. Now that your Sony VGN-FW398Y 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 Sony VGN-FW398Y battery is removed, grab your replacement Sony VGN-FW398Y battery for installation.
6. Insert the battery into the slot. Push the Sony VGN-FW398Y battery towards the laptop and secure it in place.