[Moto Z4 Guides, News, & Discussion] clevertrevor777:
Any input is welcome. I struggled a bit to get his working so I'm hoping someone else can benefit:

***As always, proceed at your own risk.***

Prerequisites:

This applies only to the XT1980-3 on the Verizon network (prepaid or postpaid). The XT1980-4 (VZW Version) is not bootloader unlockable. For clarification, the XT1980-3 is the "Unlocked", "Carrier Unlocked", or "Retail" version of the phone. I believe there are also Canada specific and US specific firmwares that are also on XT1980-3. This method should also work on the Amazon version of the phone (someone please confirm). You will lose your built in Alexa functions, and your phone will essentially be a Verizon version when completed (except bootloader unlocked, and rooted if you so choose).

Download and install the Motorola Drivers: https://support.motorola.com/us/en/drivers

Download and extract the zip file: https://www.androidfilehost.com/?w=files&flid=301320

It contains the PDF29.105-25-20 firmware, a rooted boot image (patched using Magisk), as well as adb and fastboot programs.

Step 1: Unlock Bootloader

If your phone is brand new, you will have to turn it on, and navigate through the setup process. You can skip everything except for connecting to a WiFi network (even without a SIM card in your phone). You must have some kind of data connection - either mobile data or Wifi to enable "OEM unlocking" (per step 2 below).

Power up your Z4 and enable Developer options: Under settings, go to "System", then "About phone". At the bottom, tap on "Build number" seven times.

Now go back to the "System" menu, and tap "Advanced", then "Developer options".

Scroll down and turn on "USB debugging".

Also scroll down and turn on "OEM unlocking".

Plug your phone into your PC with the factory USB cable. You should see a dialog on your phone prompting you to accept the USB debugging token. Check the box for "always accept", and tap OK.

Follow all steps from the Motorola Website and take note of all warnings. THIS WILL FACTORY RESET YOUR PHONE AND DELETE ALL YOUR DATA:

https://motorola-global-portal.custhelp.com/app/standalone/bootloader/unlock-your-device-a

You can use the adb and fastboot programs that are in the zip file. Once the zip is extracted, just open the "cmd-here.exe" to start a command window in that folder. Then you can use the "adb" and/or the fastboot" commands from the Motorola instructions.

Once you unlock the bootloader, your phone will restart.

Step 2: Flash the Verizon Firmware

You will need to get back into fastboot mode. If you have enabled "USB debugging" (again), you can type the following into the command prompt (open cmd-here.exe)

adb reboot-bootloader

otherwise, just hold down the volume-down key and power key until your phone restarts. It should now be in "bootloader" mode (aka fastboot).

Verify that you see "USB Connected" in green on your Z4.

Open up the folder you extracted, and double click "servicefile.bat". The script will run for several minutes. If the script doesn't run, and you only see <waiting for any device>, then you're not in fastboot mode, not connected to your PC, or something is wrong with your drivers. Once the script completes, scroll through the messages and make sure there are no failures or warnings. Then press any key to exit the script.

Step 3: Root (Optional)

If you want to root the phone, go back into the extracted zip folder and open up "root.bat" (while still in fasboot mode). The script will write a patched boot file to your a and b boot partitions.

At the command prompt, press any key to restart your phone.

Enjoy unlocked bootloader, WiFi and Video calling, and Root on Verizon.

If you want to verify that your phone is rooted, download and install the latest Magisk Manager apk. Look for all green check marks when you start the app. https://github.com/topjohnwu/Magisk/releases

Credit:

Batch File Creation: Root Junky - https://youtu.be/njXQYn53SPc

Firmware Download: https://mirrors.lolinet.com/firmware/moto/