iPhone 5C blow up

Hi everybody,

I just would like to know if anyone of you had this issue.

After my wife get a new iPhone 6S we let the iPhone 5c at our bedside table as not in use, but suddenly, after a couple of day there it was completely opened, I mean, looks like blow up. This is the first time I saw something like this, I have been using iPhone since 4S and had all them since 4S and this is really weird. It was turning on but we were a little bit afraid to charge it to see if all the rest is working. Pictures are attached below. So let me know if any of you had this before.