1. Turn your HP XH121UA laptop over.
2. Find the laptop battery release button lock for your HP XH121UA laptop.
3. Now that your HP XH121UA 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 XH121UA battery is removed, grab your replacement HP XH121UA battery for installation.
6. Insert the battery into the slot. Push the HP XH121UA battery towards the laptop and secure it in place.