Please try doing a factory reset on device using a Pin or Toothpick into Restore hole at device.

Step 1 – Power off device
Step 2 – Use a toothpick and press into Restore hole ( On side of device ) and keep it pressed.
Step 3 – While holding reset button power on device
Step 4 – Once you see boot menu on screen so release the reset button.
Step 5 – Select wipe data / Factory reset on Recovery menu. Then reboot device now once its completed.