Certain keys have stopped working on almost unused Apple wired keyboard

I've had a wired apple keyboard for about 6 years, been used once or twice briefly and stored in it's original box in a dry place the rest of the time. It's pretty much brand new. I took it out the box to use the other day and the ` Z X and C keys have all stopped working. Any tips or advice on how i may be able to fix this? Ive seen things about using warm water but i'm not so sure about trying that. Ive taken the caps off and used some contact cleaner to no effect and there is no evidence of any damage or corrosion under the caps. Like I said it's pretty much new and can't see how theses keys would just stop working after next to no use.

 

That's what I feared, I think you may be right. Just a shame as it's never really had any use, like I'd bought it yesterday. From what i've read there doesn't seem to be a way to open it up without damaging it and if the circuit has gone I doubt they'd be anything to see or do.
Built in obsolescence... or more likely just a dodgy one from the start.