When I received mkv file in my external card(stroge) from others and download it from net then my cellphone get too much heat and Derain all battery in just several minutes and sometimes it's damaged my all saving file .
And the biggest problem is that when I download higher graphics games from unknown sources and Google pay its not working smoothly, sometimes I faced lagging and stucking problem .some apps is not working cause they r for latest android version and mine is still kit kat .so they have need to upgrade it's tom to latest marshmallow 6.0 and this device is comfortable with new os but they not giving latest ROM, only intalnal miui from updated few times.