1. Turn your HP G72-a40SA laptop over.
2. Find the laptop battery release button lock for your HP G72-a40SA laptop.
3. Now that your HP G72-a40SA 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 G72-a40SA battery is removed, grab your replacement HP G72-a40SA battery for installation.
6. Insert the battery into the slot. Push the HP G72-a40SA battery towards the laptop and secure it in place.