My 2020 S205 has acquired an annoying squeak, which I have identified as originating from behind the N/S boot trim, located right behind the rear seat beneath the 3/4 panel window (circled in red). Applying pressure on it allows me to reproduce the squeak. Interestingly, when I park the vehicle with the brakes off and strike this place with my fist, the electronic handbrake engages.
I assume that electronics or a kind of sensor are concealed inside.
I am unable to determine how to detach the carpeted trim, since the clasp for the folding seat back obstructs my ability to remove the panel. I would really appreciate guidance or advice on the contents behind the panel and the procedure for its removal. A components diagram for the region would be beneficial.