I'm having the same issue.  I updated the system and then the gamepad became stuck on the "select a user" screen.  No response from any buttons but the home button and the tv button.  When I press the TV button it opens the tv remote screen but nothing works (volume, etc). When I press the TV button again it takes me back to the select user screen and suddenly the touch screen works again.  It won't let me select my Mii or even create a new user.  The "user settings" button doesn't work either.  Instead it just swaps the tiles back and forth between my mii and "add new user".  I'm on the phone with Nintendo now and I have to send my WiiU in for repair.  

This cannot be happening....how on earth can something so colossal occur on the FIRST day?  Gamestop has no more WiiUs to swap it out with either.  So angry right now.