1. Turn your Dell 4100D laptop over.
2. Find the laptop battery release button lock for your Dell 4100D laptop.
3. Now that your Dell 4100D 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 4100D battery is removed, grab your replacement Dell 4100D battery for installation.
6. Insert the battery into the slot. Push the Dell 4100D battery towards the laptop and secure it in place.