Hey!
I'm going to submit this to Apple Support when I'm home from Work but I'm posting it on here to see if anyone else has had this issue or knows a work-around.
Basically, my iPhone SE 64GB crashed during the night, it totally froze so my alarms didn't go off. When I finally woke up, I went to check my phone and it was totally unresponsive to any button or the screen been pressed. Flexi time is a forgiving thing, and I needed the sleep, so no real gripes there.
Fortunately, it restarted on holding home and power. The only thing in the logs is a resetcounter, which was added at the time I reset it.
It's uptime was only about 2 days, I have no apps where I specifically allow background refresh, but it's enabled as a system setting, which implies not much more than apple services run during the night. It does self-backup up to iCloud at night, but I don't use iCloud for any other apps - I'm out of reception a lot, so I avoid most apps which need constant activity.
I'm afraid to say that my last iPhone, a 6S 128GB suffered a similar fate, something happened during the night, but it never turned back on; and my replacement was also faulty.... but that's another story.
The only apps I notice as been installed or updated around the time of the crash on both my SE and 6S are Dropbox, Google Maps, and Facebook (messenger and main app).
FWIW: iOS 9.3.1, > 40GB free, 4G carrier (GiffGaff)
Cheers,
Whitling2k
