My 2000 380DA has push-in / pull-out plugs covering the wiper motors.
If that doesn't exist on your yacht, then the headliner on mine is probably retained in similar fashion to that on yours.
On my boat, the headliner fabric is attached to a plywood panel. That plywood is screwed at perimeter locations to the ceiling.
The screws are concealed by the padded upholstery fabric. On almost the entire surface the fabric is glued to the plywood. At the screw locations the fabric is not glued.
The screws are accessed by untucking the fabric edge from between the seams, pulling the fabric back to exposed the screw heads, permitting the screws to be removed.
It is possible to detect the screw locations by feeling through the padded foam for the screw heads.
Mine also has welting at certain locations. That welting is retained by RTV adhesive, so pull off, then glue back on at reassembly.