I bought Nexus 6 since April this year ans used it without any problem. But lately, I think after upgrade to lollipop 5.1 my phone started to act strange. If will turn off after used the phone about 2 hours - just reading stuff on internet. There is still 60% of battery left but it just shut itself down - black screen with empty battery icon. It is getting worst sometime turn off at only 75%. Now I downgraded back to lollipop 5.0 but still have the same problem (just did it today). Is there anyone experience the same problem? Can anyone help what should I do. Thanks