The water resistant Sony Xperia Z has some how acquired a disease that is killing the handset without any sign or warning. Actually, some Xperia Z users are complaining that their expensive Android phone randomly shuts down, never to switch back on again.
The dedicated XperiaBlog brought the issue to the limelight as a number of users are discussing this new issue where the phone turn off without their knowledge, and there is no way they can bring it back. However, a few users have managed to bring the phone back to life by hard resetting (holding power + vol up) the Xperia Z, meaning simply hold Power And Vol up button and you might get your phone back.
The fix is neither permanent nor universal, and still no real cause is known for the problem making it a lot more frustrating for the owners who bought the handset thinking it will work even under shower. Sony was quick in responding to the issue and has promised a fix for the random shutdowns, which will be applied with the next update.
Note: You need not to worry as most of the Xperia Z users hare more than happy with this powerful Android phone.