The device has a clip on a hinge, and the body itself. It is NOT possible to remove the clip without opening the body.

The body shell consists of two non-transparent pieces and a matt-white light diffuser panel. To make things easier, I'll call them "the diffuser", "the wall", and "the base".

As it turns out, the three pieces are held together with some sort of glue. The wall has about 1mm of overlap with the diffuser, where those are glued together. The same goes for the base. To swap the battery we'll have to do some prying and then gluing, unfortunately.

To start the disassembly, find the biggest gap between the diffuser and the other part. Use a flat, sharp tool. Apply pressure downward and inward on the most area possible. Don't let the tool slip, don't put pressure on one point, and be patient. Once one side gets loose, move your tool toward the end of the opening, undoing more and more glue.

It is possible to leave no scratches and cracks. Take your time, try different tools, and be careful. Little cracking noise is ok when the glue is being broken.