[Magisk] ShadeTreeBiker:
I installed magisk in recovery last night, the img created had all three options in the bottom checked. It installed correctly, did a few reboots to make sure things stuck, then installed a couple modules...Debloater and BusyBox...

Everything went fine, uninstalled a few apps, then went to the playstore and got the System Safe App uninstaller and Titanium BU. Did a pretty good backup, and even did a backup through the Partition Backup app, all went to the SD card fine.

Then when (this morning,) I rebooted it for the first time after doing all that,,,(unwisely, I might add for not rebooting repeatedly after installing/uninstalling apps, etc.) the phone ONLY boots to the bootloader...Fastboot ONLY.

I'll put the phone specs below...

I do have a raw dd .img of every partition, excepting the user part, (WAY too big, but okay.) and from fastboot I have tried flashing the Recovery, System, parts, cleared the cache, attempted to use the Magisk Uninstaller, (no good either.) Here is an edited cmd window output, (edited out all the fastboot --helps!):

C:\Users\Vic\Desktop\platform-tools>fastboot devices
320195447577 fastboot

C:\Users\Vic\Desktop\platform-tools>fastboot reboot system
fastboot: usage: unknown reboot target system

C:\Users\Vic\Desktop\platform-tools>fastboot reboot
Rebooting FAILED (Device sent unknown status code: ↕↕♣
)
fastboot: error: Command failed

C:\Users\Vic\Desktop\platform-tools>fastboot devices
320195447577 fastboot

C:\Users\Vic\Desktop\platform-tools>fastboot reboot recovery
Rebooting into recovery OKAY [ 0.003s]
Finished. Total time: 0.054s

C:\Users\Vic\Desktop\platform-tools>fastboot boot C:\Users\Vic\Desktop\platform-tools\TWRP.img.
img
Sending 'boot.img' (14508 KB) OKAY [ 0.832s]
Booting OKAY [ 0.058s]
Finished. Total time: 1.094s

C:\Users\Vic\Desktop\platform-tools>fastboot flash recovery "E:\androidwork\Z3351S\StockImages\
TWRP 3351\magiskrecovery.img"
Sending 'recovery' (17361 KB) OKAY [ 1.232s]
Writing 'recovery' OKAY [ 0.379s]
Finished. Total time: 1.670s

C:\Users\Vic\Desktop\platform-tools>fastboot reboot recovery
Rebooting into recovery OKAY [ 0.002s]
Finished. Total time: 0.008s

C:\Users\Vic\Desktop\platform-tools>fastboot boot E:\androidwork\Z3351S\twrp-3.3.1-0-twrp.img
Sending 'boot.img' (4548 KB) OKAY [ 0.277s]
Booting FAILED (remote: 'invalid kernel address: not
lie in memory')
fastboot: error: Command failed

C:\Users\Vic\Desktop\platform-tools>fastboot boot "E:\androidwork\Z3351S\StockImages\TWRP 3351\
twrp.img"
Sending 'boot.img' (12338 KB) OKAY [ 0.689s]
Booting OKAY [ 0.051s]
Finished. Total time: 0.993s

C:\Users\Vic\Desktop\platform-tools>fastboot flash recovery "E:\androidwork\Z3351S\StockImages\
TWRP 3351\magiskrecovery.img"
Sending 'recovery' (17361 KB) OKAY [ 1.980s]
Writing 'recovery' OKAY [ 0.379s]
Finished. Total time: 2.389s

C:\Users\Vic\Desktop\platform-tools>fastboot boot recovery
fastboot: error: cannot load 'recovery': No such file or directory

C:\Users\Vic\Desktop\platform-tools>fastboot reboot recovery
Rebooting into recovery OKAY [ 0.003s]
Finished. Total time: 0.052s

C:\Users\Vic\Desktop\platform-tools>fastboot flash recovery E:\androidwork\Z3351S\StockImages\r
ecovery.img
Sending 'recovery' (24576 KB) OKAY [ 1.744s]
Writing 'recovery' OKAY [ 0.535s]
Finished. Total time: 2.329s

C:\Users\Vic\Desktop\platform-tools>fastboot reboot recovery
Rebooting into recovery OKAY [ 0.003s]
Finished. Total time: 0.010s

C:\Users\Vic\Desktop\platform-tools>fastboot reboot
Rebooting OKAY [ 0.003s]
Finished. Total time: 0.009s

C:\Users\Vic\Desktop\platform-tools>fastboot flash system E:\androidwork\Z3351S\StockImages\sys
tem.img
Invalid sparse file format at header magic
^C
C:\Users\Vic\Desktop\platform-tools>
C:\Users\Vic\Desktop\platform-tools>fastboot devices
320195447577 fastboot

C:\Users\Vic\Desktop\platform-tools>fastboot erase cache
******** Did you mean to fastboot format this ext4 partition?
Erasing 'cache' OKAY [ 0.012s]
Finished. Total time: 0.063s

C:\Users\Vic\Desktop\platform-tools>fastboot continue
Resuming boot FAILED (remote: 'not support on security')
fastboot: error: Command failed

C:\Users\Vic\Desktop\platform-tools>fastboot reboot system
fastboot: usage: unknown reboot target system

C:\Users\Vic\Desktop\platform-tools>fastboot boot E:\androidwork\Z3351S\StockImages\recovery.im
g
Sending 'boot.img' (24576 KB) OKAY [ 1.636s]
Booting OKAY [ 0.104s]
Finished. Total time: 1.990s

C:\Users\Vic\Desktop\platform-tools>fastboot flash E:\androidwork\Z3351S\Magisk-uninstaller-201
91102.zip
unknown partition 'E:\androidwork\Z3351S\Magisk-uninstaller-20191102.zip'
fastboot: error: cannot determine image filename for 'E:\androidwork\Z3351S\Magisk-uninstaller-
20191102.zip'

C:\Users\Vic\Desktop\platform-tools>fastboot disable-verity
fastboot: usage: unknown command disable-verity

C:\Users\Vic\Desktop\platform-tools>fastboot flash recovery
fastboot: error: ANDROID_PRODUCT_OUT not set

C:\Users\Vic\Desktop\platform-tools>fastboot flashall
--------------------------------------------
Bootloader Version...: k39tv1_bsp_1g-cded285-20190711093946-20190715113906
Baseband Version.....: MOLY.LR12A.R3.MP.V50.3.T0643
Serial Number........: 320195447577
--------------------------------------------
fastboot: error: ANDROID_PRODUCT_OUT not set

C:\Users\Vic\Desktop\platform-tools>

I NEED HELP!!!!

As you can see, I've tried EVERYTHING I know of...except flashing every partition one at a time...BUT I guess IF it's a necessary evil, okay...BUT I have to get this thing back up. I'd like to retry Magisk core only along with a DM-Verity disabler...I THINK that's what went wrong, I may have actually succeeded in a system alteration...unintentionally, as the DM-Verity was still in place, (as far as I know.)

Love it, and as far as I can tell I MAY be the first one to achieve root with this device, I couldn't find anyone or anything else that had. It SEEMS to be A/B supported, (it's in the init.rc,) but when I checked if it was a system-as-root it returned nothing, but the ramdisk in the boot.img file is empty...an indicator I believe IF I am understanding all those changes correctly.

Here's the poop on the phone

ZTE Z3351S (MT6739) (Q-Link Govt phone)

Android 9 (2019-07-05 security patch)

So, I guess, THANKS to ANYONE willing to read this to completion, and even MORE thanks to the one with an answer!

;)