iPad Air 2 not turning on
My own iPad Air shut off by itself last month (with the charge reading at 80%) and wouldn't turn on, even when I plugged it in. After 30 minutes of it being plugged in, the screen was still black. However, I left the iPad charging for about an hour and finally the screen came back on.

Try charging it for an hour, and plugging it into iTunes to see if you get a response from it.