My Sony Xperia ZL is NOT booting up unless it has an external power supply. The phone vibrates, shows the SONY bootscreen, and then dies. Also, the phone runs perfectly until i disconnect it and it simply dies in the blink of an eye. I have an unlocked bootloader and was on CM10.2, flashed the stock ftf for 4.3, then 4.2, and yet nothing worked! My device is just around 8 months old and i doubt that my battery can be dead all of a sudden when it was giving decent backup until today!
(couldn't get a reply on the ZL forum that's why posting here)