You have to put the phone on safe mode which will disable all downloaded apps. To do this power off your device and the power it on, while its powering on after it vibrates for the first time hold the volume up and down button in amd wait untill the phone boots with small text on the bottom left saying safe mode. After this go into your setting and delete the app 360 security or any other that could be causing problems and then reboot the phone it will go back to normal.