There is a rare bug which has happened to a handful of users after an OTA update. We don't know why it happens, but when it does it can break your navigation bar, lock screen, and status bar. You're unable to use your home or recents buttons, see your lock screen, or pull down to see your notifications. This is incredibly annoying and personally, has caused me to factory reset in the past. However, there is a fix that you can try, and it involves setting up your phone again - or at least tricking your phone into thinking you've done so.

https://www.youtube.com/watch?v=Xun2x6e0i00

Video of the bug in action


How to Fix the Broken UI After an OTA Update

So while we still don't know why exactly it seems to be a bug, we know it can be fixed by completing the Android Setup Wizard once again. What happens is that the settings that Android Setup Wizard stores to tell the system that the setup process has been complete have been reset. After first boot these settings should never change, however, it seems it may randomly reset after an OTA update.

There are potentially two ways to fix this. If you have Developer Options already unlocked and USB debugging enabled, then you'll be able to use an adb method which is a guaranteed fix. If you don't have USB debugging enabled and can't access it, then you'll have to try another method which is not guaranteed to work.

ADB Method

Open a command prompt or terminal window and enter the following:

        adb shell
    
        settings put global device_provisioned 1
    

Then wait for the command to complete. This took about 10 seconds for me.

        settings put secure user_setup_complete 1
    

And now you are done! Once these commands are run, you should immediately be able to control your device once again.

You can also run those commands from a terminal application on your device, such as Termux. Make sure your device is rooted with Magisk or SuperSU if you choose to do it this way, and instead of typing "adb shell" type "su".

[appbox googleplay com.termux]

Activity Launch Method

If you don't have adb already set up, the process is trickier. Download an app called Activity Launcher.

Activity Launcher Developer: Adam Szalkowski
Price: Free
4.1
Download

Open it up and tap up top to see all activities on your phone. Scroll through the list and search for "Setup Wizard." Go through and tap on each of the activities listed under Setup Wizard to see if it will launch the setup process again for you. Hopefully one of them will work. If not, your last remaining option is a factory reset.


Explanation

What this does is simply edit the Secure Settings values that tell Android you have finished the initial set up process. You may be wondering why if the device thinks you haven't completed setup, or why the setup application isn't launched. What's happening is, the device denies access to the UI elements which would let a user escape the setup process. Normally this is a good thing, however, in this case it denies you access to your device even though you've already set everything up. When you complete the setup process, those two settings we edited in the "adb method" above are changed to 1, but thankfully by doing that change ourselves we can get around this silly bug.