Hi. Yesterday when my phone had less than 60% of the battery charge, it turned off, I tried to turn on, but I could not. Then I plugged it and it reported 60% of charge(with the phone off), after 2 minutes I turned it on and in the notification bar it was in 3%. Today it was the same problem, when it happens it is overhead. Also it loose the Wi-Fi password. I don't know if it is a battery problem or software problem.
My phone is a Xperia Z 6603, with Android lollipop 5.0.2
Thanks.