The faceplate is held on by two plastic clips near the battery screw.

Starting with the top clip is easier, as it's easier to get a grip of the faceplate once it pops out a little bit. Use a spudger to prevent it from popping back in, but holding it in place with your fingernail is also possible.

Push in the holes with a bent paperclip or SIM eject tool with minor force.

Pushing slightly off-angle (as indicated by the arrows) can be much easier due to the internal shape of the clips, so it is recommended to do it this way to prevent damaging the plastic.

Once both clips are undone, the faceplate lifts off like turning a page in a book backwards.

Lift the left side, and lift it upwards and right.

Then it should be possible to just lift it upwards to remove it.