Be gentle! Using the small flat-head screwdriver, you can now carefully (!) lever the front case slightly ajar (2mm should be enough) to disengage the plastic lug at the position marked 1 in the picture.

After that you can remove the bottom plastic cover completely by pulling it carefully in direction of arrow 2 and wiggling it slightly. It helps to hold the camera upside down, so that the plastic shell above the battery contacts (2nd photo) does not fall off. (If this piece accidentally becomes detached, simply plug it back on the contacts again).