I dropped my Otter Box-encased iPhone 6 (fully charged) from 3 feet to a tile floor, and it went absolutely dead. Wouldn't turn on. Took it to the AT&T store where I bought it, they tried these tricks, no dice. Told me to drive it 90 miles away to my nearest Apple store. Took it there, the repair guy wasn't on duty, the desk guy pressed all the same buttons the AT&T guy and I had pressed, for the same amount of time. No dice. Wait-- it gets even worse.
Next day, went back to the AT&T store to upgrade to a 7+ (and got a new iPad). While the tech guy was synching my phone and iPad, it claimed I had NEVER backed up my iPhone, BUT-- my old iPad had been backed up. Relief! Since it had been synched with my iPhone 6, my photos taken with my dead iPhone 6 were still on it. BUT...gradually, my photos disappeared from my old iPad. And when the tech went back to check, my new iPhone was showing my old iPad had NEVER been backed up.
With the history of back-ups erased on my old equipment, years' worth of my pictures have now disappeared.