1. Turn your Sony PCG-4F2L laptop over.
2. Find the laptop battery release button lock for your Sony PCG-4F2L laptop.
3. Now that your Sony PCG-4F2L 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 PCG-4F2L battery is removed, grab your replacement Sony PCG-4F2L battery for installation.
6. Insert the battery into the slot. Push the Sony PCG-4F2L battery towards the laptop and secure it in place.