Having had an issue with the Caps Lock keycap suddenly popping off and being told by Apple that repair would entail replacing the entire case (to which the keyboard and trackpad are permanently bonded to) at my expense to the tune of ~$800, since that was a "cosmetic damage" not covered by warranty, I doubt you will get satisfaction from them.
I would suggest wrapping the screen up securely for protection, popping the corresponding keycaps off, then turning the Mac upside down and spraying the key mechanisms clean with high quality contacts cleaner. The idea is to flush the contaminant out without letting it and the spray solvent creep into the guts of the Mac. Have someone hold the Mac upside down while you spray upwards. Will probably also be a good idea to mask off all but the keyboard with good quality non-residue painters's masking tape. Since the scissors mechanisms under the keycaps may break when popping them off, you can get replacements at https://www.replacementlaptopkeys.com/ where they also have how-to videos.
Lastly, this pic of my broken-off Caps Lock may give you an idea of how they're put together (click to zoom). The springback action is provided by the round silicone rubber "cup" enclosing the electrical contact in the center.