I thought I'd pass on my experience with a battery problem with one of my two iPhone 6s that was solved by a DFU +iTunes restore. TLDR: try it, it might work for you. I have two iPhone 6s. One was bought on launch day, the other less than a week later. Both are set up nearly identically. The second one was actually "built" originally by doing a restore of the backup of the other phone. Generally they have performed very similarly in terms of battery use, but in the past couple of weeks one of them has been draining its battery very quickly overnight. The installed apps are almost exactly the same and the settings are exactly the same (and set up to maximize battery life), so that was annoying. I've read posts saying that restoring from an iTunes backup will simply reinstall whatever the problem was, which sounded logical. I've read posts going both ways on whether or not restoring from an iCloud backup would reinstall the existing problem. Logically, the best solution would be to rebuild the phone from scratch, but that would take a lot of time, so I figured that I'd try the simplest, fastest solution and see if it worked, since there was no downside. Bottom line: restoring in DFU mode from the iTunes backup seems to have completely solved the problem. The phone that was getting significantly worse battery life is now doing slightly better than the other one. I thought I'd post this in case you have assumed, as I did, that restoring from an iTunes backup wasn't likely to solve your problem. My recommendation: give it a shot if you're having problems that you can't trace to obvious settings problems.