If you have any IOS device with 64 bit, then this information is for you. All latest iPhone models from iPhone 5C and upwards, iPad air, iPad mini and iPod touch devices shouldn’t be changed date back to 1-1-1970 or earlier. Many users reported that, there is bug in IOS that bricking all the devices mentioned above when they changed the date of device back to 1-1-1970. If your mobile bricked with this setting, it can not be restored from iTunes or in any way. Rebooting will not help too. Apple aware of this issue and they are trying to release an update to fix this issue. So until next update, please don’t try to change the device date earlier than 1-1-1970.
If you already changed the date and if your mobile is bricked, reach out for nearest apple showroom. They will suggest, what to do next. Many users reported that, they exchanged these bricked mobiles with working one’s but you should be under warranty period.