Flip over the enclosure so that the circuit board is on the bottom and the optical sensor is on top.

Remove the screw on the optical sensor using a Phillips #00 screwdriver.

Remove the tape on the red and black wires that connect to the optical sensor. With the wires still attached, take the sensor off the ensclosure.

The wires on the optical sensor are very weak. They will break easily if excessive force is applied to them.

Remove the four black screws on the edges of the enclosure using a Phillips #00 screwdriver.

After taking out the screws, you don't have to open the enclosure just yet.