Update to Android 8.0 gives Android Recovery screen

I did OTA 8.0 upgrade, now N6p boots, flashes time, boots again and gives:

Android Recovery
8.0.0/angler/angler
user/release-keys
Can't load Android system. Your data may be corrupt.
If you continue to get this message, you may need to
perform a factory reset and erase all your user data
stored on this device
Try Again
Factory Data Reset

Last 2 lines toggle with volume, select with power.

What can I do?