xperia s battery drain

Hi, after 3 happy years with my xperia s, here it is a major issue. Three weeks ago, in the middle of a phone call my xperia shuts down (battery at about 85%) and no mean to restart, it was like dead. No led if in charge or connected to my pc. After three days, a friend opened the phone, pull of the battery, reconnected the battery and, here it goes, it started again. But, another issue now, battery drains at 10% each hour in stand by. I changed the battery with a new one, same thing, i had a hard reset, same thing. Battery status shows 30% consumed by the screen (but it was only 15 min !) and google services 25%. Anybody has an ideea how to fix it ? Thanks for your answer.