(couldn't get a reply on the ZL forum that's why posting here)
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!