It appears that the bug affects all iPhones with a 64-bit CPU — A7, A8, A8X, A9 and A9X chips — but it doesn’t matter which version of iOS is running.
Some users have tried changing the date on their device and were still able to boot their device. For those who got away with trying this and it not bricking your device, there’s a reason why – time zones.
In some time zones, setting the date to 1 Jan 1970 will set the internal clock to a number less than zero, as the time is stored in GMT (as the number of seconds since midnight on that date) and then the offset is applied before display. In other time zones, setting the clock will result in a positive time value. Best guess is that this is triggered by having the time value less than zero.
How to fix this:
At the moment, the only way to make sure no one, purposely or accidentally, bricks your phone is to have a jailbroken iPhone and install the BrickingDate tweak.
All you have to do is to install the tweak on your jailbroken device. You’ll first have to add a new source to Cydia by opening the Sources tab and tapping Edit -> Add. A new pop-up appears where you’ll have to enter the following repository: http://repo.ziph0n.com. Once added, search for the tweak’s name and install it on your iOS device.
It is most likely that Apple will fix this issue in iOS 9.3, so until then all the non-jailbroken users will have to be extra careful and wait.
Good news for non-jailbroken device!
It was found that disconnecting the battery and reconnecting it will allow the iPhone to reboot, however take caution while disconnecting the battery.
Follow these instructions to properly disconnect the battery from your device without causing damage: