I had the same experience the previous day, i tried removing the battery method, it did work but the problem still was persisting on the next restart ; same issue was continuing. so i tried the traditional method of switching off and praying for the computer to work, but hours passed no results. then i thought , before this issue i had a problem on the mousepad not working or got stuck, so i pressed the f8 key in the keyboard which stand for "nullifing the mousepad" to disable it. then the mouse pad started working. so i pressed the f8 key two times, then there came a menu showing automatic repair, i choose to restart them . after restart same problem came back again, then i tried my previous method of pressing the f8 button two times, the loading symbol was shown and my computer worked. i don' t know it was due to my prayer or my luck of trying this new method. but it worked and that matters.