Hi, I went to use my iPad air which I'm sure had plenty of charge left in it and found it had gone off or ran our of charge? It was not turning on and so I plugged in to charge. It did not start To charge at all and so I left it for a few hours as I know sometimes it takes a while to start charging if the battery is completely empty. After a few hours it was still lifeless! So I decided to try the hard reset by pressing the home and top button simultaneously. Thankfully the screen came on indicating that there was no charge and so plugged it in and it started to charge. Now my question really is does anyone know why this happened? Or is there anything potentially wrong with the device ? I'm wondering whether something is wrong with the battery? Many thanks for your help.