Ok, I suggest installing the latest oreo 8.1 firmware for your phone. Download the correct version for your phone, copy the firmware to SD card, do hard rest and after flash the firmware. Good luck
I suggest you try again, but first do a hard reset.
Download the firmware again and copy to SD card.Turn off the phone, then press and hold the Vol down button for about 2-3 seconds.
Keeping these buttons pressed, press the power button for a short ...