Let's try to root the Note Pro Android 9, firmware 3.1

[Markismus]

1. Download update.upx
I've used the script of @winstonma to download the update.upx.
2. I've modified the script to rename instead of remove update.upx and the unencrypted update.zip. After unpacking update.zip you'll find the file boot.img.
3. I've installed magisk, clicked install in the app, unclicked recovery and choose the boot.img file. It generated the file magisk-patched-23000_X4h1q.img. (The last part of the filename is just random letters.)
4. Hooked up the Note Pro to the PC (Linux). Copied the img-file to PC.
5. Gave the following commands as root:

[root@pc]# adb devices
List of devices attached
K3T8R520N5  device

[root@pc]# adb reboot-bootloader
[root@pc]# fastboot devices
K3T8R520N5  Android Fastboot

[root@pc]# fastboot reboot recovery
Rebooting into recovery                            OKAY [  0.000s]
Finished. Total time: 0.050s
[root@pc]# fastboot devices
K3T8R520N5  Android Fastboot

[root@pc]# fastboot boot ./magisk_patched-no-preserve_no-recovery.img
Sending 'boot.img' (9044 KB)                       OKAY [  0.259s]
Booting                                            OKAY [  0.000s]
Finished. Total time: 0.265s
[root@pc]# fastboot devices
K3T8R520N5  Android Fastboot

[root@pc]# fastboot oem unlock

(It hangs on the last command. On any command after fastboot boot image.img)
No luck yet! It doesn't boot and hangs on any further commands of fastboot. Holding the power button disables the Note Pro and holding it again restarts it. No harm nor success.

Did anyone have more luck? Should the recovery switch be turned on? I've followed the threads on rooting for the Max3 and the Lumi and they have success with this approach.

There are 2 switches Preserve force encryption and Recovery Mode. So that's four images that can be generated: I'll try them first. All four fail.

[yokos]

Using the execute command inside fastboot command is unusual for me.
Did you get something like that?

downloading 'boot.img'...
OKAY [ 0.276s]
booting...
OKAY [ 0.002s]
finished. total time: 0.301s

For Max Lumi I have used this:
[x] Preserve force encryption
[ ] Recovery Mode

[Markismus]

@yokos I've expanded the commands with the results. I've chosen the safer route of first seeing whether it boots, before flashing.

According to this question on stackexchange, it could just not be supported by this device.
However, I did see you mentioning it in your thread.

"Using the execute command inside fastboot command is unusual for me.

What do you mean with this?

[winstonma]

Please check your PM

[Markismus]

Thanks @winstonma! I tried using a patched recovery.img with the toggle preserverd encryption. But it still won't work with the fastboot boot command:

[root@pc]# adb pull /sdcard/Download/magisk_patched-23000_zkFBH.img ./magisk_patched-from_recovery_preserved_recovery.img
/sdcard/Download/magisk_patched-23000_...d. 9.1 MB/s (16732160 bytes in 1.745s)
[root@pc]# adb reboot-bootloader
[root@pc]# fastboot devices
K3T8R520N5  Android Fastboot

[root@pc]# fastboot reboot recovery
Rebooting into recovery                            OKAY [  0.000s]
Finished. Total time: 0.050s
[root@pc]# fastboot boot magisk_patched-from_recovery_preserverd_recovery.img
fastboot: error: cannot load 'magisk_patched-from_recovery_preserverd_recovery.img': No such file or directory
[root@pc]# fastboot boot magisk_patched-from_recovery_preserved_recovery.img
Sending 'boot.img' (16340 KB)                      OKAY [  0.467s]
Booting                                            OKAY [  0.000s]
Finished. Total time: 0.481s
[root@pc]# fastboot devices
K3T8R520N5  Android Fastboot

[root@pc]# fastboot reboot
Rebooting

Did anyone succeed at booting or flashing a magisk-patched image for the Note (Pro)?

[winstonma]

Please try to flash the patched recovery in fastboot mode. Skip the command

fastboot reboot recovery

and see if it helps

[Markismus]

It doesn't help for the fastboot boot image.img command.

As for flashing, I am still not to clear about the repercussions. The image based on the recovery image is 16M, while the boot.img are 8M, so it seems that you have to flash them at resp. recovery and boot.
As I am messing about with the booting, it seems unwise to experiment with the recovery partition, because I will need that one if things go amiss, right?

So rather than the recovery.img, I should be using the patched boot,img for flashing? Or am I confusing things here?

[winstonma]

First of all, magisk-in-recovery method is not the same as patching boot.img way. So don't worry it would work. Yes you are right the patched recovery.img is 16MB.

adb reboot-bootloader
fastboot devices
fastboot flash boot patched-recovery.img

Please let me know if it doesn't work for you