Go to recovery.
Power off your phone. Hold both volume buttons and the power button at the same time. When the phone vibrates, let go of the power button but keep holding both volume buttons. In a few seconds you should be in the recovery menu.
Use volume buttons to move up/down and power button to select. Go to format data/factory reset and select it. Next, select format cache partition. Now select reboot and see if things are normal.
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