If the left “Win” key seems not to be working under Linux then it could be that the “Fn” and “Win” keys have been switched.
In order to switch them back you can hold down left “Win” together with “Esc” for about four seconds. The Caps Lock backlight will flash three times indicating that the switching process has completed. In order to switch them back I think you can hold “Fn” together with “Esc” for about four seconds again and wait for the three Caps Lock backlight flashes.