1. Turn your HP ZE4400 laptop over.
2. Find the laptop battery release button lock for your HP ZE4400 laptop.
3. Now that your HP ZE4400 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 HP ZE4400 battery is removed, grab your replacement HP ZE4400 battery for installation.
6. Insert the battery into the slot. Push the HP ZE4400 battery towards the laptop and secure it in place.