pess the power button for more than 10s to shut down the phone , and then press  volume+ button and power button, when you see the boot animation, loosen the power button. and then the phone will enter the recovery mode. if you have backed up your data before,select the clear data and then reboot

Try again,It takes time,Press volume+ and power button try again,If you can't enter the recovery mode ,Plz go to the after-sales center