The core device can actually be accessed by the bottom; screws are hidden under the rubber pad.

The rubber pad is simply glued to the bottom, you can easily unstick it from the shell to gain access to the screws.

Be careful to only pull the rubber part and not the entire bottom. I initially tried to force it out and figured out the screw location by breaking it... don't do that.

Under the rubber pads are 4 Philips screws to get inside.