Some weeks ago I got a Xperia Z Tablet for free. The former owner was unable to charge it. A plugged in charger didn't do anything. As the battery was already dead, the Xperia Z Tablet only showed a 3 times blinking red light while pressing the ON button, I thought that it could be the charger itself. I tested 3 different chargers one with even 2.1A. Some forums suggested that the tablet should be charged for a longer time, some suggested 24 hours, I let the tablet on the charger for that long, but it didn't charge.