The lower part of the circuit board seems to extend quite a bit underneath the casing. So instead of prying, I pull - to no avail.

I try with a small set of pliers to get a better grip, grabbing the board by a corner so as not to damage the circuitry. I manage to get the board out a bit further, but then it's stuck and I soon see why: The USB charging port is caught on the casing.

If I don't want to risk tearing it off or at least damaging it, I can't proceed this way.