On the silver ring located on the outer edge of the plastic portion of the subwoofer, you will see four 2.7 mm screws. Use a Torx T10 screwdriver to remove them, in order to remove of the subwoofer.

Once the four screws have been removed, gently pull the subwoofer out as to not damage the wiring connecting the subwoofer to the main board inside the unit.

Follow the wires from the subwoofer to the main board and disconnect the connector attaching them.

Your subwoofer is now disconnected and ready to be replaced.