perfect ipad mini - dead?

We have two ipad mini's purchased together about 2 years ago. A few weeks ago one of them stopped working? It hasn't had any physical damage, it was simply fine one evening and the following morning it was completely dead. The screen is blank with no signs of power, it doesn't respond to being left plugged in to charge and when we plug it in to the computer it isn't recognised as even being there, itunes also doesn't see it.

We have followed the Apple trouble shooting instructions, and nothing. Not sure what else to try?