1. Turn your Fujitsu T4020D laptop over.
2. Find the laptop battery release button lock for your Fujitsu T4020D laptop.
3. Now that your Fujitsu T4020D 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 Fujitsu T4020D battery is removed, grab your replacement Fujitsu T4020D battery for installation.
6. Insert the battery into the slot. Push the Fujitsu T4020D battery towards the laptop and secure it in place.