1. Turn your Sony VGN-CR520EJ laptop over.
2. Find the laptop battery release button lock for your Sony VGN-CR520EJ laptop.
3. Now that your Sony VGN-CR520EJ 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-CR520EJ battery is removed, grab your replacement Sony VGN-CR520EJ battery for installation.
6. Insert the battery into the slot. Push the Sony VGN-CR520EJ battery towards the laptop and secure it in place.