I went to get the new ios running today and hit a problem. itunes synced to my device just fine and I proceeded to download/backup for an hour or so but when itunes started to prepare my ipad for the goods, the ipad switched off and I got a, "New hardware detected" or "Apple recovery mode?" pop up. I installed/updated the drivers and whatnot so I don't get the "New hardware detected" or "Apple recovery mode?" anymore. Instead I just get nothing as the I pad wont show up in itunes. The I pad itself didn't just turn off, it went completely unresponsive. It will not: respond to a charge, turn on, or 'reset'. An attempt to plug into different usb does nothing. I wonder why.
I am not sure if your problem is the same as mine was; but my iPad wouldn't turn on or charge or anything either. The solution I found was to plug in to charge; hold the home button and the power button for approx. 15 seconds. Mine started up just fine and has worked perfect since then.