Turn-Off Gate
Probably restored from backup. Leave your old junk from that 3GS behind.
This is a natural feature of every smartphone. If you're doing something extremely taxxing on the processor, it may shut off because of overheating. Perfectly normal.
Had this today for the first time on my iPad mini 3![]()
Have had it on numerous occasions with an iPhone5 and iOS7. Same solution applied though. Never thought much of it but a small annoyance.I had this problem on the iPhone 6 iOS 8 some months back
Only happened one time