After removing the screws under the rubber pads, the backplate should gently fall off under it's own weight. If not, help a little with plastic opening tools.

Now you have access to the SD card, the raspberry pi 4 compute module, the Intel WiFi Chip, the battery, and the builtin 8 Ohm 2W speakers.

Taking apart the unit further than this holds the risk of damaging it significantly, so only progress with lots of caution.