Apple has officially acknowledged the “January 1, 1970” date bug affecting 64-bit iPhone, iPad, and iPod touch devices. Apple said that an upcoming iOS software update will prevent the issue from occurring in the future.
Manually changing the date to May 1970 or earlier can prevent your iOS device from turning on after a restart. An upcoming software update will prevent this issue from affecting iOS devices. If you have this issue, contact Apple Support.
Manually changing an iOS device’s date to January 1, 1970 results in a continuous reboot cycle, effectively bricking the device.
Apparently, there are rumours floating around that setting your iPhone’s date to January 1, 1970 will activate a cool ‘retro theme’ for your phone. This is false. Here is the report from ‘Snopes’.