1. Turn your Sony VGN-CR309E laptop over.
2. Find the laptop battery release button lock for your Sony VGN-CR309E laptop.
3. Now that your Sony VGN-CR309E 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-CR309E battery is removed, grab your replacement Sony VGN-CR309E battery for installation.
6. Insert the battery into the slot. Push the Sony VGN-CR309E battery towards the laptop and secure it in place.