The electronics for the Mystery Dreidel are attached to a separate cardboard CPX holder. The holder is the length of two squares, the same size as the sides of the cube section of the dreidel body. One half has a window cut out of it to allow the lights to shine through that side of the dreidel. It also serves as a handle so you can slide the electronics in and out of the dreidel easily.
To assemble the electronics, plug the battery pack into CPX.
Stick an adhesive dot on the back of the CPX. Attach it to the top of the battery pack (the side with the On/Off switch).
Use another adhesive dot to glue the battery pack to the bottom of the CPX holder. Make sure it is centered!
To keep the dreidel balanced as it spins, you may want to add some weight to either side of the battery pack. I used additional adhesive dots to attach a battery to each side.
Hold the back flap like a handle and insert the CPX holder into the dreidel. It should sit level on the bottom of the middle cube portion of the body.
Also check that you can see the cut-out letter (Hey) through the window in the back of the CPX holder.