Gently pull flat band out of the circuit board mount. You might use the pliers but don't bend the band.

Move the 3 wires out from the gap between the casing and circuit board.

First: White

Second: Orange

Third: Black. This is the one we need to free.

Now the back casing with circuit board should come lose. Only attached by the black wire.

Also pull out the 2 metal mounting plates.