The same thing happend to me...will not charge with TouchStone or Touchpad charger. Thought the unit was bricked. No matter what button combo, etc..nothing happens!!!!
To fix this, on a hunch I plugged in a Samsung phone charger which for some reason I could see that the app close button on the front of unit immediatey started flashing. After a few minutes, the charging symbol appeared and then it complained it was the wrong type of charger. Immediately, I plugged in the normal charger and voila!! Working again!!!
Can't figure out why this happens, but each time it is because of an accidental and complete discharge. For some reason, the regular charger will not kick start the charging process. This has happened to me twice now.