Asus MeMO Pad 10 won't power on?

I have a MeMo tablet that won't turn on. It does charge (the LED will turn green after awhile). I've tried all the various button-holding suggestions, poking the reset button, opening it up and leaving the battery unplugged for a time, and even swapping the battery with a known good one (I have two of these), but nothing has made any difference. The device was working fine, and then suddenly just stopped. It was not dropped or bumped recently. Any suggestions?