[Nvidia Shield TV & Shield TV Pro (2019) Questions ] powercommy:
See also https://xdaforums.com/showpost.php?p=81200005&postcount=380

Below are the steps we used to root our Nvidia Shield 2019 PRO, if you are new to rooting devices you better can wait until their are less steps.

For some reason this post doesn't show correctly in the XDA app.

UPDATE: it's possible to use the official release of Magisk.

PreRequisites:

Download: Experimental TWRP is from https://xdaforums.com/showpost.php?p=80769929&postcount=312

Download: Magisk official release https://github.com/topjohnwu/Magisk/releases/tag/v20.4

Download: Filename: nv-recovery-image-shield-atv-pro-2019-8.1.0-dev-rooted.zip (see above post)

Download: Filename: nv-recovery-image-shield-atv-pro-2019-8.1.0.zip (see above post)

Working ADB/Fastboot.

Coffee and a bit of luck.

Enable Developers options/Enable USB Debugging/Authorize device.

Step 1

Reboot to bootloader to start fresh...(you will need a keyboard)

Use files from filename: nv-recovery-image-shield-atv-pro-2019-8.1.0.zip

Use vbmeta_skipped.img from filename:

nv-recovery-image-shield-atv-pro-2019-8.1.0-dev-rooted.zip

a) fastboot oem unlock and confirm by pressing A

b) fastboot flash staging blob

c) fastboot flash boot boot.img

d) fastboot flash recovery recovery.img

e) fastboot flash system system.img

f) fastboot flash vendor vendor.img

g) fastboot flash dtb mdarcy.dtb.img

h) fastboot flash vbmeta vbmeta_skip.img

I) fastboot -w

j) fastboot reboot bootloader

Step 2

Now we will boot to twrp and install magisk...

a) fastboot boot twrp.img (you will need a mouse for this)

b) select mount and mount everything it lets you (usually data, system_root, vendor, cache)

c) adb remount all

d) adb shell

e) rm /system (removes symlinked folder)

f) mkdir /system

g) mount -o bind /system_root/system /system

h) exit

i) adb push Magisk-v20.4.zip /data/media

j) In twrp press install and navigate to magisk zip and flash it

k) adb reboot bootloader

l) fastboot -w

m) fastboot reboot bootloader

n) fastboot flash dtb mdarcy.dtb.img

o) fastboot flash vbmeta vbmeta_skip.img

p) fastboot reboot

q) let it reboot a couple of times, after Nvidia blinks and then reboots).

Optional

r) If Shield doesn't go passed the Nvidia logo.

s) start shield with A+B pressed to get in fastboot

t) in fastboot menu select reset factory default.

u) fastboot flash dtb mdarcy.dtb.img

v) fastboot flash vbmeta vbmeta_skip.img

w) fastboot reboot

x) let it reboot a couple of time

Step 3

Device eventually loads.. when it does follow these steps

a) Enable usb debugging

b) make sure its authorized and connected

c) adb install -g magisk.apk

d) adb shell

e) su (grant root to shell when it pops up)

f) mount -o rw,remount /

g) Go to apps (trough settings), show all apps, start/open magisk manager

h) When it pops up telling you it needs to install stuff select ok and install it.. device will reboot in 5 seconds...

Step 4

When device tries to boot you should now be stuck at the android boot ani (NOT the nvidia logo).. then follow these steps..

a) adb shell

b) su

c) resetprop ro.boot.verifiedbootstate orange

d) after device boots run: resetprop ro.boot.verifiedbootstate green

Step 5

If you have registerd for the hotfix (32.7.301.43) then you can start the upgrade now. The device will reboot and starts the upgrade, after that you lost root again.

a) adb reboot bootloader

b) fastboot boot twrp.img (you will need a mouse for this)

c) select mount and mount everything it lets you (usually data, system_root, vendor, cache)

d) adb remount all

e) adb shell

f) rm /system (removes symlinked folder)

g) mkdir /system

h) mount -o bind /system_root/system /system

i) exit

j) adb push Magisk-v20.4.zip /data/media

k) In twrp press install and navigate to magisk zip and flash it

l) adb reboot bootloader

m) fastboot flash dtb mdarcy.dtb.img

n) fastboot flash vbmeta vbmeta_skip.img

o) fastboot reboot

p) When device tries to boot you should now be stuck at the android boot ani (NOT the nvidia logo).. then follow these steps..

q) adb shell

r) su

s) resetprop ro.boot.verifiedbootstate orange

t) after device boots run: resetprop ro.boot.verifiedbootstate green

After every reboot

When device tries to boot you should now be stuck at the android boot ani (NOT the nvidia logo).. then follow these steps..

a) adb shell

b) su

c) resetprop ro.boot.verifiedbootstate orange

d) after device boots run: resetprop ro.boot.verifiedbootstate green

Stuck at Nvidia Logo

a) Power off Shield, remove power cable

b) Press & Hold A+B on keyboard or controller.

c) Plugin power cable will holding keys.

d) You will see the fastboot menu.

Restore Stock

Use files from Filename: nv-recovery-image-shield-atv-pro-2019-8.1.0.zip

a) Power off Shield, remove power cable

b) Press & Hold A+B on keyboard or controller.

c) Plugin power cable will holding keys.

d) You will see the fastboot menu.

e) fastboot flash staging blob

f) fastboot flash boot boot.img

g) fastboot flash recovery recovery.img

h) fastboot flash system system.img

i) fastboot flash vendor vendor.img

j) fastboot flash dtb mdarcy.dtb.img

k) fastboot flash vbmeta vbmeta.img

l) fastboot -w

m) fastboot reboot bootloader

n) fastboot oem lock and confirm by pressing A

Like I mentioned before, only use this when you know what your are doing. I'm not responsible for any brick devices.

All the credits are for @elliwigy and @rootfan