From this point you can easily choose which process to complete next; you can boot recovery mode, wipe data, clear system or use ADB commands through your computer. (android.gs)
Check the info below only if you know your way around the tablet's recovery mode, as it will have you install manually the Android 5.1 Update using adb sideload commands. (android.gs)
To do that, I dug into the source code of Android 8.0 once the final release dropped, and discovered the existence of ADB shell commands that could enable or disable overlays, which XDA Writer Adam Conway covered yesterday. (xda-developers.com)