[Moto G4 Plus Guides, News, & Discussion] calinb7:
Took my Nougat (and finally got my Verizon plan to deliver 4G on my MotoG4 Plus)!

My XT1644 was stuck in slow 3G mode after switching from ATT to Verizon. It's a bug in the phone that sometimes renders it incompatible with Verizon 4G. (See Lenovo/Motorola forums) that is fixed with Nougat. Now, after the OTA update, my phone works in 4G again! I've learned that unrooting is harder than rooting, but I struggled though it all, thanks to Bender1987's excellent guides.

I've learned much, but I also still have some questions (and maybe some answers too ;)), as follows and all based on my experiences only. I'm certainly not an expert yet--like many here in xda!

Unless you disable the updates using root tools, rooting does not stop OTA notifications or even downloads. However, the updates will not complete the install process successfully when rooted. Furthermore, if you agree to install updates after the notification while rooted, the installer will also delete the installation file upon its failure. After the download completes, I say "no" to the install. Then I use TWRP to navigate to the installation file (in the location described by Bender) and I copy it to sdcard for side loading later (when not rooted). I also use TWRP's mtp interface to transfer a copy of the install file to my computer for permanent archiving, just to be safe!

I'm still puzzled about this point, Bender. I used your guide to root my phone. I have never flashed TWRP (I always just fastboot TWRP when needed). Before rooting, I used TWRP to backup everything TWRP can backup. However, when I used TWRP to restore boot, and system (and wipe caches) and I also restored logo with fastboot, OTA failed. Then I noticed that the Motorola update process that I had frozen using rooted SDMaid, was still frozen! So I re-rooted and unfroze the update process, and restored my TWRP backup again. I still got 1004 "system failed to verify" or something to that effect! I had to download the 1+GB file from FileFactory to restore my system with fastboot as you describe in the OP, but I don't understand why my TWRP backups were insufficent.

Why does a restore of a TWRP system backup (in addition to TWRP boot restore) fail to restore my phone for OTA updates? Keep in mind that my recovery is stock and I also restored logo with fastboot. When I rooted my phone, only boot, system, and logo should have changed. It would be nice if we could rely on our own TWRP backups instead of downloaded images from the Internet!

adb never works for me so I never use it. I use the buttons on my phone (which can require several attempts, because they are picky about timing) and fastboot. No ADB is required. fastboot and TWRP are the only utilities I've ever used to root and un-root my phone (though gMTP comes in handy too).

I had the same warning but I successfully restored and took the Nougat update, regardless. I must assume they were not corrupt, because the Nougat installer would have failed. Based on the message, I conclude that they must not have been signed, for some reason or other.

When the OTA popups occurs and your phone is rooted or also not in stock form, (except for the data partition, which may be modified) you should only download, but NOT install! It is okay, however, to keep you bootloader unlocked. I've never relocked my bootloader and I've rooted and unrooted a couple of times now and also successfully taken the Nougat update.

If you choose to install the update after the download completes and the above requirements are not me (as bender describes in the OP), the installer will delete the update install file AND the app_download subdirectory after it fails. You can try again and restart the OTA process by selecting "settings" >> "about phone" >> System updates but DO NOT agree to install it when the warning about installation time and emergency call service, etc. pops up. I use the filemanager in TWRP to copy the update file to a safe place (/sdcard for side loading later) and I also mtp it to my computer too! gMTP works for me with TWRP.

adb doesn't work at all for me so I never use it and I'm not surprised. You don't need to use the mount command and you can do everything you need to do with phone button presses, fastboot, and TWRP!

Restoring system and boot TWRP backups, and logo using fastboot was not enough for me. (I never flashed my recovery and I've always kept it stock.) Even though I had the TWRP backups, they were worthless for me (I like to know why.) I had to download and fastboot all the images as described in the OP.

Cool! I didn't know about this tool! I used rooted SDMaid to freeze the Motorola update process (it's normally set to "BOOT"). However, it did NOT unfreeze after I restored my TWRP boot and system backup. I had to re-root and enable it with SDMaid and then restore from TWRP again. I still had problems and eventually had to fastboot all the system images from the OP. I have no idea if that would have unfrozen the Motorola process. (If Android were GNU/Linux, it would have--haha!)

XT1625 and XT1644 appear to use the same, according to the filenames (and txt file info therein):

http://www.filefactory.com/folder/c6cdedc45a775d27/?sort=created&order=DESC&show=100&page=2

Nope--not a senior moment mark, Bender was just abbreviating the toolnames (madb and fastboot); it's not a folder/subdiectory name!

adb doesn't work for me so I've never used it at all. I used phone button presses, fastboot, and TWRP (booted upon need and never flashed). I don't see that adb / madb offers much, once you get the button press timing down.

Update:

I decided to try to get adb working again and it's working for me now. The problem was all the tapping, checking boxes, and "dancing" around you have to do on the phone to enable this developer feature. Luckily, there are many quides and threads online, but I still don't think it's terribly useful for the rooting, un-rooting, and OTA updating tasks discussed here.

I'm still very concerned that I had to flash the entire system partition from an image in order to install an OTA update. This is supposed to be "systemless" rooting after all! Thus, I've learned that I cannot rely on a TWRP restore in the future either. (It wasn't sufficient this time.) AFAIK, there is no way to save reliable non-rooted system snapshots (like full disk images with dd) after taking an OTA. Motorola does not provide any partition snapshots for post-OTA updated ROMs.. In order to take or install a new OTA, a user may find that they need to save and re-install the chain of ALL previous OTAs, after re-rooting (rebuilding the phone's entire update history after flashing the original system image each time). I know that's not what people expect to need to do but I fear it may be the truth--at least it seems to be, based on Nougat OTA experience.

Thus, I will never install an OTA update without first saving and archiving the OTA file for future use. A complete archive of the original images AND the entire chain of updates ensures that I can re-root but still reliably restore my phone to accept future updates.