Plugging in this date will permanently crash your iPhone
The bug affects devices on iOS 8 or 9, which includes the iPhone 5s or newer, iPad, iPad Air, iPad mini 2, and iPod touches made in 2015 or later. Techie commenters on Reddit and elsewhere note that’s the start of Unix time, a way for developers to track time as a running total of seconds.
The date will effectively turn your phone into a mobile brick.
Why would you reset the date and time on your phone to 46 years ago? Though Unix time can be negative, possibility exist that something related to the time zones is crashing the iPhone.
It further added that users in America, with time zones behind GMT, were affected, but one user with the time zone set to Beijing did not.
There are several videos of people demonstrating what happens when they set their clocks back to January 1, 1970.
Reddit users tweaked with the settings change to report that their phones and Apple devices wouldn’t reboot and they had to bring them into an Apple store to get fixed or scrap them all together. But powering off the phone and then on again results in a perpetual greeting screen, with the Apple logo just staring back at you for the rest of time.
A precautionary tip for all you iPhoners! just stay in the present, that way is better for your iPhone device.