just got the gopro out, its not been used for about 10months. The battery is ok, i checked it with my mates.
It might be broken.
On a more helpful note, have you tried powering it from the usb? Mine wouldn't turn on once, but it would after plugging it into the pc and it's been fine since.
Mine stopped working after a period of none use.
Turns out the on/off button had some crap in it and wasn't moving enough to turn it on.
still not working!
checked the buttons, still not any life!
I'd contact Gopro and ask (is it under warranty?) I broke a couple of mounts and they were brilliant about dealing with that, no hassle, no receipts or owt.
I take it you were checking the buttons without the external case?
It's over 18 months old. I opened it right up and cleaned it.