Well, at least for mine, I ever treated it as my little baby. Never drop, never too cold nor too hot conditions, never dropped a single drip of water... Just used perhaps too much! I think 2 or 3 hours of usage a day, it became my main internet access point at home and my pim while travelling (75% of my living days), the object I used to pass time watching some film, playing during spare time or browsing when away from home thanks to a pesudo flat (500Mb per month) contract with my phone operator.
Yes, I simply think it went out of order due to too much use, some sort of wearing!
Filled in the warranty form, still waiting for it to come back. BTW, only defect had been the crack near the usb port. Oh, and the screen became ghosting on the left bar of the hildon interface due to screen persistance. Yes, I really think simply too much use It had a lot of scratches, too. Only a hard dust particle was enough to scratch the screen. Probably I played lucasfilm adventures (ah, Monkey Island!) too much...

Is there any feedback on the above repairs -- how much did they charge etc?
I've just had the same problem on my 770 and since I got it on eBay it won't be a warranty repair.

It is somewhat disturbing because there is no obvious sign of physical damage so I don't know what made it fail.

It's covered by warranty if it was built < 1 year ago. I sent mine in w/out the receipt. Of course I am still waiting for it. You can check to see if it's still in warranty via nokia's site too.

http://www.nokiausa.com/support/warr...,1965,,00.html