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 near the hinges. Lift the cover off of the system. Find and disconnect the battery cable. Identify the 4 cell battery and loosen the 3 screws securing it. Lift the battery out of the system.
To reinstall the 4 cell battery, place it back in the system and install the 3 screws. Reconnect the battery cable. Place the cover back on the system and install the 8 screws.