[Android Auto General] BostonDan:
Ok, so after countless hours I was finally able to get AA Mirror to work on my car again. These were my steps and mileage may vary based on phone, etc. My steps do include using Android Auto Display Emulator https://developer.android.com/training/auto/testing/ prior to syncing with the car. Also, this method does require root to use AA_Unlock and AA_Mirror, both of which may be downloaded from https://github.com/slashmax/AAMirror.

1) Go into settings -> Apps & Notifications -> See all apps.

2) Click the three dots on the top and press "Show system"

3) Go down to Google Play Services

4) Click Storage

5) Click Manage Space

6) Click "CLEAR ALL DATA" *** warning, this will erase your bluetooth connections, such as Wear OS from watches. There are ways to resync your watch without performing a full reset by following https://www.xda-developers.com/pair-android-wear-without-factory-reset/. This will also remove your current connection to your car which will have to be re-synched.

7) Reboot your phone (Not certain if this is required, but I did reboot my phone)

8) Start Android Auto on your phone (the phone is not attached to anything at this time)

9) click on the menu on the top left (three bars)

10) Click "About"

The following steps may already be done. I am including them for reference for newbies.

<reference steps>

11) If developer mode is not enabled, click on the bar "About Android Auto" 10 times.

12) click on the three dot menu (on the top right)

13) click on "Developer settings"

14) click on Application Mode and set to "Developer". Also go to the bottom of the developers settings and make sure "Unknown Sources" is checked.

</reference steps>

15) click back, and then go to the three dot menu. Click "Start head unit server".

16) connect the phone to the computer

17) open a command shell

18) type "adb forward tcp:5277 tcp:5277"

19) navigate to <sdk>/extras/google/auto. This is usually found at "c:\users\USERNAME\AppData\Local\Android\Sdk\extras\google\auto"

20) start the desktop head unit with the command "desktop-head-unit"

21) accept all the permissions, etc.

At this time you should see the typical head unit display that you would see in your car.

22) click on the lower right speedometer symbol (to return to Sync, or other OS).

you should see AA Mirror 1.0 listed. If it is not, click on "All car apps".

23) Click on AA Mirror 1.0. Your phone should prompt you to grant root access. Accept root access.

24) Stop the Desktop head unit (click the x on the top right).

25) go to your car. Turn on your car and connect your phone to start Android Auto. Accept all the permissions requests, etc.

26) Turn off your car. Disconnect your phone from Android Auto.

27) Now, go to your apps, and start AAUnlock

28) Grant AAUnlock root access

29) hit the button "Unlock". You should see toast messages (if you have them enabled) that says that "Superuser Request from AAUnlock" and after 1-2 seconds "Done. Reboot Phone"

30) reboot the phone

31) Once the phone reboots, connect the phone to your car, and start Android Auto. Go to the speedometer thing (on the lower right side of the screen) and see if AA Mirror is listed. If it is, give thanks below. If it isn't, I don't know what to tell you.

Hope this helps somebody.

Cheers,

B.D.