To remove the 3 cell battery. Remove the 8 screws securing the base cover. Pry the cover away from the recess points near the hinges. Pry the cover off the system. Identify the battery cable. Use the pull tab to disconnect the battery cable from the connector on the system.
Loosen the 4 screws securing the battery. Lift the battery out of the system with the cable. Remove the latching tape. Flip the battery over. Disconnect the battery cable from the connector on the 3 cell battery. To reinstall the three-cell battery. Reconnect the cables on the battery connector. Flip the battery over. Retape and reinstall the latch.
Place the 3 cell battery along with the battery cable. Tighten the four captive screws to secure. Connect the battery cable to the connector on the system board. Put the base cover on the system. And tighten the eight screws.