Moto G 2 screen doesn't go off

[AC Question]

While i push the power button, it says shutting down and keep on circling but does not turn off for 10 or 15 minutes. I do not have option to take out the battery as it is inbuilt so i kept on pressing power button but nothing much happens.

Then all of a sudden it starts booting up. Now i am worried about it.

Any help ....