My tablet was on power and the video was playing while downloading windows 10 to upgrade from Windows 8.1. I was out of the office for one one and when I came back I found the tablet is off. On my surprise when I turn it on it starts and I sign in it displays the desktop for few seconds and turns off. Or if I turn on if I don't sign in it will also shut down for hardly 30 seconds. Please can any one help me how to solve this problems, I fail to get to the automatic repair or diagnostic test and repair. Please I need your help.