If the phone is still unable to boot to the Home screen, you may need to reset the phone to factory settings. Since the phone will not boot properly, the factory reset can only be performed using special commands outside of the device settings. See How do I perform a factory reset using hardware buttons? for details.
If the phone continues to
experience problems after the factory reset or the reset cannot be
completed, you can reinstall the software, which will also delete
all content on the phone and install the latest software version.
For phones with Android 5 Lollipop or higher, Device Protection may be enabled, which means that after the factory reset, you'll need to sign in using the same Google® Account that was logged into your phone. If you forgot your Google® Account password, use your computer web browser and go to www.google.com/accounts/recovery to reset your password first.
To perform the factory reset: