[Moto Maxx Q&A, Help & Troubleshooting] ChazzMatt:
rooting Motorola Marshmallow 6.0.1 firmware

Well, I solved it

April 7, the very day you posted.

It just took until April 12 for me to repeat it two more times for you to actually listen. ;)

Using so-called stable or even newer SuperSu for initial root will cause bootloops for Motorola Marshmallow 6.0.1. Only that older beta SuperSu works on many Motorola Marshmallow firmware. I'm not going to say "all" Motorola Marshmallow firmware -- but many, many, many. AFTER you get initial root and confirm that status (after reboot), then you can update to newest SuperSu. It's only an problem on initial (first) root.

We discovered it in the Moto Quark (Moto Maxx/Moto Turbo/Droid Turbo) phones, as well as Moto Kinzie (Moto X Force), and here's even a thread for 2015 Moto G3 with the same issue:

How to get root 2015 Moto G3 With Stock Android Marshmallow 6.0 (XT1541)

https://xdaforums.com/2015-moto-g/general/root-how-to-root-moto-g-2015-android-t3320113

I wrote the bootloader unlock and rooting guide for the 2014 Moto XT1225 and Moto XT1250 (Moto Turbo/Moto Maxx) and it's in there.

UPDATED GUIDE: How to unlock your MOTO MAXX/MOTO TURBO bootloader/install TWRP/root

https://xdaforums.com/showthread.php?t=3455341

Months later when the sibling Quark Droid Turbo XT1254 was updated to Marshmallow, that beta SuperSu requirement still applied.

[GUIDE] How to unlock your Droid Turbo bootloader, install TWRP and gain root access

https://xdaforums.com/showthread.php?t=3292684

Also applies for 2015 Kinzie, the Moto X Force (sibling to the Droid Turbo 2)...

[ROOT][INFO][MARSHMALLOW] How to Root Moto X Force 6.0 [TESTED]

https://xdaforums.com/droid-turbo-2/general/root-how-to-root-moto-x-force-6-0-t3282151

and probably many other Motorola phones.

With the Quark phones, we first discovered it with Moto Maxx/Moto Turbo XT1225 in July 2016. I updated my bootloader unlock/TWRP/root GUIDE for the XT1225 to include that information specific to stock Motorola Marshmallow firmware. The XT1250 Moto Maxx has still not received official Marshmallow but it will apply to them also if/when it happens.

THEN, in December 2016 when the Droid Turbo XT1254 got Marshmallow they ran into the same problem -- but the XT1225 is identical Quark phone except for radio (and the Droid Turbo has a Verizon-mandated locked-down bootloader which has to be jimmied with Sunshine). We XT1225 owners already knew what to do and told them! So, [MENTION=5901115]TheSt33v[/MENTION] updated

his Droid Turbo guide

to convey the same information.

It was the first thing I told you if you look back up the this post thread. I asked if you were using the correct SuperSu for Motorola Marshmallow and that the procedure had changed, so my guide was updated in July 2016 to reflect that. That's why I even put "UPDATED" in my guide title. And I also said after you get initial root (and confirm), then you can update the SuperSu to newest if you wish.

_____________

What build prop editor are you using? I use this one:

BuildProp Editor

https://play.google.com/store/apps/details?id=com.jrummy.apps.build.prop.editor&hl=en

You also have to give your build prop editor app root privileges in SuperSu. Go into the SuperSu settings and see all the apps which have root approval. In the SuperSu logs you can also see the apps which had been denied root privileges. In the SuperSu app settings, I always change the pop up root request to "30 seconds" so I am sure to see the root request.

Do NOT try to do both build prop changes at the same time. Let's keep it simple. Do the DPI change first, reboot, see if it took effect, then do the other. You can easily mess up your phone trying to do too many changes at the same time.

Make sure you have a TWRP backup before doing any build prop changes. It might be the ONLY way to recover from a disaster.

1) DPI

Be careful about messing up your display. For instance Motorola stock Quark DPI is 640, which I actually prefer. But [MENTION=5747496]bhb27[/MENTION] and other ROM developers make the DPI smaller to a default 560 DPI. For instance, in Resurrection Remix in Settings/Display here's the choice to go larger and smaller, if you wish.

But 550 is NOT one of those choices. Maybe that's a strange DPI our 1440p AMOLED displays can't handle? Try 560 and see what happens. If it still doesn't change, we'll discuss further.

2) VIRTUAL KEYS

You are SURE this is the correct command for our Quarks? There's TWO different commands for virtual button prop edits for Android phones all over the internet:

http://forums.androidcentral.com/showthread.php?t=390680&p=5262529&viewfull=1#post5262529

Which one works with our Quarks? I don't know. Also mentioned in this article:

Disable or Enable The On-screen / Virtual Software keys In Android!

http://www.gizbeat.com/2021/disable-or-enable-the-on-screen-virtual-software-keys-in-android/

I haven't found either command in my build prop editor on Resurrection Remix -- a ROM which allows virtual buttons to be enabled. Maybe because I haven't actually enabled virtual buttons and the ROM would add those commands when I did so? Anyway try BOTH commands -- but not at the same time! Try one, reboot. If it doesn't work, try the other. You may have to add the lines manually in edit mode, but again make a TWRP backup first before making any changes.

If neither command works, then you'll have to ask one of the Quark ROM devs what command they use to permit virtual buttons to be enabled.