You may have heard previously about a bug that caused any iPhone or iPad to be unusable when you set the device’s date to January 1, 1970. This was due to an issue where the Unix real value for a Date/Time on iOS was May 1970, which resulted in dates before then to have a negative real value. This resulted in services running on the iPhone to crash and fail to load, resulting in a phone that had to be restored to be used again.
The issue has now developed, which cripples devices, especially iPads and iPods, causing them to overheat consequently destroying their batteries. Hackers can set your device’s date-time back automatically, as most devices synchronize their system clock with a time server.
Security researches Patrick Kelley and Matt Harrigan created their own fake NTP (network time protocol) server which can trick apple devices using Wi-Fi to reset the date, causing them to brick without the owner’s interaction. However, when they did this they noticed that changing the system time before the minimum date led to the iPad overheating and time started counting backwards, all whilst heating up slowly as time counted backwards.
The iPad supposedly reached temperatures as high as 55 degrees celcius (130F) after just 15 minutes of testing, with it becoming too hot to touch by the time the device counted back to 1965.
The vulnerability was patched in iOS 9.3.1 and we recommend you update any iOS devices to this date.
Sources:  http://www.tomsguide.com/us/ios-1970-bug-weaponized,news-22538.html