A post made on the Facebook page of Sony Mobile Hong Kong revealed the existence of a physical button to hard reset the recently launched Sony Xperia Z Ultra phablet. Not many Sony phones pack a hard reset button, so the discovery of this one comes a quite a surprise. It's not too difficult to find the button, a tiny red colored spec which can be spotted only if you're looking for it by opening the micro SD card slot flap. Holding the button with a pencil for 5 to 10 seconds will hard reset your phone, which can be done in case your handset freezes/completely stops responding.
Check out the image posted below to know exactly where the button is located.