Do the normal thing with the T6 Torx screw.

Grab the front of the speaker in one hand and the back cover in the other, and rotate the back clockwise slightly. It should rotate just a few millimeters.

Four lugs inside are disengaged when it rotates. You can now gently lift the back cover away. Be careful not to put strain on the ribbon cable.

Using a plastic spudger, unfasten the zero insertion force (ZIF) connector latch. Slide the ribbon connector out of the ZIF connector to free it.