What we can do is when a phone got no reaction , unplug the device and if you left it overnight if that's nothing we can do about it , still no reaction we plug to the charge ,and on it , (that ) once the device cool down it should reboot
once we left it to cool for a few hours, meaning it drain off the power empty , battery devices seems to have this problem, obviously we cannot open the iphone and disconnect the battery to it Mainboard ,, unplug the power supplied , just left it a few hour let it drain off the power supplies!! Hope it help