1. Turn your Sony PCG-FX804 laptop over.
2. Find the laptop battery release button lock for your Sony PCG-FX804 laptop.
3. Now that your Sony PCG-FX804 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-FX804 battery is removed, grab your replacement Sony PCG-FX804 battery for installation.
6. Insert the battery into the slot. Push the Sony PCG-FX804 battery towards the laptop and secure it in place.