I bought a new iPhone SE about a month ago. Nice phone. Like it a lot. Works fine. However . . . I went outside yesterday afternoon. Phone was fully charged. Walked over to a local coffee shop, sat down, took out the phone, and it wouldn’t respond. Nothing. Dead. Fortunately, I’m close to an Apple Store. So, I walked over, checked in, and was seen by a rep at the fix-it counter. He plugged the phone in. Unplugged it, then pressed the buttons in sequence and the phone booted. I entered my code and all was good. I asked him what was going on and he said that the phone will sometimes “shut down” when going from a warm to a very cold environment to save “battery life.” This makes no sense to me but what do I know. Anyone ever heard of this or seen this behavior.
By the way, the key combination is Volume-up, then Volume-down, then Power button (hold for 20 seconds). You do that in sequence.
That’s the force-restart sequence. It will forcibly power-off and restart a phone, in the event that nothing else works.
It should only be used if in fact you have no other choice. it’s the functional equivalent to pulling the power cord on a desktop system. But in a case like yours, where the normal power-off/power-on sequence isn’t working, it is your only remaining option short of opening it up and disconnecting the battery.
As for why your phone crashed in this way, I don’t know. It clearly wasn’t a simple power-off, or the side-button would have restarted it without the force-restart sequence. Something in iOS or the hardware crashed, maybe due to the cold, but that’s about the most I can figure out from this description.
Thanks. Yeah. I mean, basically the phone was just sitting in the pocket of my jacket. So, I did the same today–same jacket, about the same temperature outside, walked to the same coffee shop, and no problem with the phone. I don’t think I could have accidentally powered it down while it was in my pocket (since you have to slide the confirmation) and, even if that had happened, it should have restarted with a simple press of the power button. If it happens again, I may ask Apple for a replacement.
It could be an app that crashed and didn’t release control, even to the Home Screen. It happens. It would look like the phone was shut down, even though it really wasn’t.
Sometimes the solution to that, if you keep seeing it, is to get a backup (to iCloud or an encrypted computer backup), factory reset the phone, and restore from backup.
Hmm. Interesting. Hadn’t thought about that. Hadn’t thought about apps crashing on iOS at all, but, then again, why not? I have an iCloud backup, yes. That’s how I set up this current phone. Don’t have that many apps on the phone, but it’s always possible that one of them misbehaved.