I have a Droid Incredible, purchased in June 2010. Recently, part of my touch screen became numb and there was no touch response (not helpful when you're texting) - that's definitely a defect. The only physical damage done by me to my phone is that there is a crack in the lens cover that goes over my camera lens - a single crack. The lens/camera eye isn't damaged and the camera still takes great pictures like the day it was taken out of the box. I spoke with both a tech rep at a Verizon store and a rep from the Verizon customer service phone line who both said that I "should be fine" and that this shouldn't affect the warranty, both also said that they're only looking for big damage; i.e. - cracked touch screen, liquid damage, physical abuse more than wear-and-tear. However, they didn't really sound confident, and only said that I "should be fine".
So I got a replacement phone anyway since it's still under the 1 year warranty. My replacement Incredible came in yesterday and it's in perfect condition.
Here's the worst case scenario with sending my old phone back to Verizon with the cracked camera lens cover: the warehouse looks at my old phone and determines that the crack in the lens cover puts the phone out of warranty, meaning that I will have to pay up to full retail price of the replacement phone that they sent me (up to $600).
Has anybody every had to send back there phone with, at least, a similar situation that was under warranty? How did it turn out? I don't expect anyone who has been in the exact same boat as me, but your thoughts would be helpful and appreciated.