I have been hitting a serious problem on my iPhone SE 64GB Space Grey (running 9.3.5, also hit it in 9.3.1) for the past few weeks which sounds identical to this problem last year affecting iPhone 6s/6s+ until it was apparently fixed in iOS 9.1: http://forums.macrumors.com/threads/iphone-6s-other-ios-devices-not-waking-up-confirmed.1922995/ I'd like to know if this is a common issue or if it's just isolated to a small number of devices. Symptoms While idle, the iPhone randomly shuts off and requires a hard reset to reboot. At first (a few weeks ago) this happened just once, at night while charging. Then it happened a few days later. Now it has been making the phone almost unusable since it happens up to 20 times per day. It occurs sometimes while the phone is in my pocket or sitting on my desk with the screen off. It never has happened while I'm using it or it's connected to the computer over USB. Other Details The first time this happened was after connecting to some devices via Bluetooth for the first time. Since then I've been keeping Bluetooth off though, and still hitting it. Also the time it started was around the time the iOS 10 update was pushed to my phone (I have not installed it), and around the time my unread email count exceeded 65536 (down to under 20k now). The only diagnostic logs are logging my hard resets, there is no indication of an app crash or low memory situation first. Attempts to Resolve - Restored from a backup via iTunes - Setup as a new phone, copying over only sms and contacts - Upgraded from 9.3.1 to 9.3.5 (haven't yet tried 10) - Uninstalled most non-default apps - Reset all settings - Turned off iCloud - Turned off wifi/bluetooth/cell data, and tried going into airplane mode - Turned off Touch ID Etc... I will probably try upgrading to iOS 10 this weekend, and will go to the Apple Store next week. There are no useful diagnostic logs though, so I'm concerned they will not be able to diagnose the issue, and if they replace the phone it may just happen again (it sounds like the 6s/6s+ problem was a software issue).