Talking from experience here, I just dissasembled mine a few minutes ago for a hardware problem, while I was attempting to take the lid off the Aluminum chassis, I accidentally torn the power button, which ended underneath the inside "beehive plastic cover".
Whe it was time to re assemble everything, I put back the power button on the top left corner, which is actually where It should be, and turned to just be held by a crappy plastic piece, which shafts the sliding movement to an actual switch, connected by a ribbon cable to the keyboard board.
Haven't searched yet, but I don't really know where I could buy this pretty specific thing, unless I get it 3D printed. Since we have the same problem, if I get it solved I'll tell you how to do so.