This is a prerequisite for working any further on the electronics box. It is far easier to set aside the speaker casing and work on the electronics box alone.
Remove the 8 Phillips screws from the back of the speaker.
Carefully remove the back panel, lifting out the metal electronics-box with it.
There are two silver, 6 mm-long machine screws with two 1/8" inner-diameter washers on the exterior of the metal electronics box; remove these first using a #2 philips screwdriver.
There are five of the same type of machine screw (silver, 6 mm-long) remaining around the metal electronics box's exterior; remove these as well.
Remove the portion of the metal housing that you freed with the 7 screws in the previous step.
Inside the metal electronics box housing is a white clip attached to a small PCB; remove this.
Snake the clip head through the hole in the metal electronics box casing.