For removing the two grilles you have to loosen the four (2x2) black screws with a Torx 8 screwdriver at the top of the grilles. You have to pay attention to the two snaps in the middle of each grille.

Loosen the Main PCB by removing the four black screw of the PCB.

Battery - Gently lift the battery with a dull plastic part. The battery is put in place with an adhesive foil under it. Pay attention to not harm the battery or the cable routes under it.

Flat-Cable - the Flat Cable under the Battery is also hold in place with an adhesive tape and snap in at the bottom side of the PCB. Pay attention by lifting the PCB.