short of returning the unit, you can call sharkoon and send them pictures, and request they overnight the parts you paid for, on them.
its a momentary switch and as such any momentary switch will do the job. I have used magnetic reed switches on pc's that require a magnet waved over the right spot on the desk to turn on.
a trip to the home depot or equivalent shop should get a temporary solution (any momentary switch) that is more elegant that using a screwdriver each power on.