I dropped my iPhone on a sidewalk in December, shattering the screen. Apple sold me a new one for $200. After I restored my backup to the new phone, within a couple weeks the iPhone started pressing the home button by itself. That is, it would jump out of whatever app I was in, then jump back and forth between the first page of the home screen and the search page. Sometimes it even woke up by itself. (sidenote: do iPhones dream of electric sheep? Probably not, that would be too google-ish!)
When one of these fits happened, the home button would activate about 5 times and then relax for an hour or two.
The phantom home button presses happened off and on for about two weeks, then faded to a much lower frequency, low enough that I would
forget and be surprised at each new occurrence.
Next, the camera turned flaky; saving pictures would take an inordinate amount of time. Then the camera app took to crashing!
Finally it happened. I tried to take a narcissus photo after getting my hair cut, there was a POP! the iPhone screen went black.
After pressing the wake button and trying to do a hard reset several times, all I could get was the apple logo in the middle of the screen. Never before had a silver apple been so agonizing!
Luckily, the closest apple store had a genius bar opening. They were able to reset the iPhone to factory defaults, and advised me to NOT restore the phone from the back-up. This was the third set of hardware using this back-up image. The theory held config cruft was causing software glitches, resulting in the behavior I'd seen.
The iPhone also stores a log of hardware errors; the reset had cleared that log, too, though.
I was suspicious. I figured if i was going to get them to replace the hardware, though, I'd have to jump through their hoops first.
Fast-forward through hours of recreating all the old settings, and days of routine use, and the phantom home button presses returned.