[X Style (Pure) General] Ohmster:
Hmmm, you have the right phone and I know this works. I did mine along with three of my friends. 2 of them needed help, one of them could not do it and lost WiFi, finally I got him rooted. One friend did his on his own and helped me. I helped the lady with Hangouts and voice chat. The last friend needed help over email and borked his WiFi but got it back by restoring his clean TWRP backup. He had all sorts of problems, like hanging on the big M. I had those issues too and unless there is really something wrong, going into TWRP and wiping cache and dalvik under Wipe/Advanced will clear it up and you can boot. Be careful and ONLY check dalvik and cache.

If stuck at the big M, force a reboot to TWRP by holding the Power and Volume Down buttons until device shuts off. Hold Power and Volume Down until device boots back to boot manager, use volume keys to get the word "Recovery" on the screen and press Power to enter TWRP. Now wipe dalvik and cache, then reboot and wait for the one time app count.

Sounds like you either need the wipe or have a contaminated system. You have to make a clean TWRP backup right after installing TWRP to restore, so if your root attempts fail, you can restore the clean system to try again. I am running SuperSU 2.65 and it works great. Very easy to install. You have the zip on the phone. You boot to TWRP, you tap Install and find the SuperSU zip file and swipe to install it. Reboot and you are rooted with SuperSU in the app tray.

If you want to force a "systemless root", you can do this prior to installing the SuperSU zip file. I did mine like this but you do not have to. It only prevents SuperSU from putting the su binary in your system partition. You still cannot take OTA updates with root installed.

To force SuperSU 2.65 and up to install systemless:

Boot to TWRP and tap Terminal in Advanced.

In TWRP Terminal, enter the command:

"echo SYSTEMLESS=true>>/data/.supersu"

Check Systemless in Terminal with:

cat /data/.supersu

Make sure it returns SYSTEMLESS=true

Or do it again and get it right this time.

From TWRP flash flash Supersu 2.65 or higher.

Reboot.

Before SuperSU 2.62, things were very different. Those early versions overwrote your system.img file with a cooked version that would work with SuperSU. That is no longer required and if you have tried this or other methods and have failed, then you probably have a contaminated system and should restore the clean backup if you have one, then install SuperSU 2.65 or higher, properly. If you get stuck at the big M with stitching, reboot to TWRP and wipe dalvik and cache in Advanced wipe, then reboot and allow the dalvik to rebuild. ( x out of 121 apps, etc.)

That is it, it should work. If you have a contaminated system (Probably got your system.img overwritten and must restore it.) and no backup to restore, you messed up. Only way I know to fix that is to download the Clark system rom and use the Recovery-System.bat file in Windows to restore a clean system back to the phone and then root it. Find that file in Post #185 above.

That is it, it will work. A little tap on the XDA Thanks Button will go a long way here if you find this stuff useful and need or want more. ;)