To remove the 4 cell battery, loosen the 8 screws on the base cover of the device. Pry the cover away from the recess points at the hinges. Lift the cover off of the system. Find and unplug the battery cable. Identify the 4 cell battery and disconnect the cables.
Remove the screws securing the battery and lift it out of the system. To reinstall the 4 cell battery, place it back in the system and tighten the screws to secure it. Reconnect the cables. Place the cover back on the system and install the 8 screws.