Not sure if this is the same problem, or if this will help, but...
I had the same thing happen to me this past summer. I'd been out running with it one day, and it MAY have gotten a little wet inside. I can't imagine what else might have happened to it.
The next day, it refused to turn on. I left the battery cover off for a while in the hope that it would dry out, but no luck. Putting in a new battery didn't help, and there is no reset feature on this player.
I put in a request for return with iRiver but they took a loooong time (weeks) to get back to me. In the meantime, after much fiddling, I manged to get it to turn on; usually after removing the battery, replacing it and pressing the power button a bunch of time. However, it would only turn on every ten tries or so.
After a couple of weeks of this, it spontaneously starting working again. The power button is a little picky still. You have to push it "just right", but I can get it to turn on with every attempt. When iRiver finally responded, I figured it was just easier to keep the player, since it was working. Kind of glad I did, as it's still working now 5 months later, but it was a bit of a gamble, I guess.
Anyway, sorry for the long-winded reply, but my point is: don't give up on the player right away. While you're waiting for iRiver to get back to you, be persistent. Fiddle with it a bit and you might get lucky, too.
