1. Turn your Dell B120 laptop over.
2. Find the laptop battery release button lock for your Dell B120 laptop.
3. Now that your Dell B120 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 Dell B120 battery is removed, grab your replacement Dell B120 battery for installation.
6. Insert the battery into the slot. Push the Dell B120 battery towards the laptop and secure it in place.