OMG! An iPhone 7s Exploded in China

Every smartphone tends to be exploding nowadays. I'm sure you've heard how Samsung Galaxy Note 7 phone has been acting as time-bomb, now an explosion case as been recorded on iPhone 7s In China
How it Happened
As reported by a user who ordered iPhone 7 Plus in China. According to the Reddit user, a co-worker pre-ordered the iPhone 7 Plus and was excited to get it, only to be greeted by an exploded phone.
“Something happened between the factory and delivery" says the owner of the phone

Samsung has been sued couple of times for copying most of Apple's design and technology, but this time around, Apple has copied Samsung's explosion feature, lol. Please what do you have to say about this, what could have caused the explosion?