[General Questions and Answers] TEFjLONjDON:
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As long as odin says "success"!! Then you should be golden.

In fact your success might also be attributed to the boot loop not being able to auto-wipe and restore the factory recovery before TWRP had a Chance to take hold.

No doubt that TWRP contributed to the success of CF-autoroot for this device & 5.1.1 software combination.

Heres My story...

I too have the metro pcs galaxy s5 on android 5.1.1... All be it.. it's 5.1.1 now because of an OTA firmware update that T-Mobile released. I downloaded it because I intended to root the stock 5.1.1 android image..

( and that is what I achieved, two S5's fully rooted on stock 5.1.1 image, with custom recovery, and customized and de-bloated to my liking)...

I was previously rooted on 4.4.2 with this S5, So I flashed the stock T-Mobile firmware I got from samfirwares.com using Odin3 v3.10.6 to esentaly unroot and get stock 5.1.1.

My device having already been rooted before on 4.4.2, would not alow me to OTA to the 5.1.1 update that Metro PCS pushed via the network.... (My wife's non-rooted S5 however; was able to receive it via the network so I rooted hers the same way as mine following same steps minus flashing the stock firmware with odin after first using mine as the guinea pig.)

That said.. After first reboot of stock 5.1.1. Firmware I verified my fears and indeed root had been broken.

I then immediately returned to download mode and flashed TWRP via Odin, after reboot I then immediately booted to TWRP recovery and flashed the waiting CF-autoroot.zip I had placed on SD previously while on 4.4.2. .... So.. root was easily achieved

Thanks to TWRP..

If I remember correctly I did have the same need to pull the battery after flashing TWRP via odin.. due to hanging on the Samsung logo....

To sum this up:

1. I'M ON STOCK 5.1.1 WITH TWRP AND ROOT ON MY S5.

2. Knox is not tripped, (update its now tripped thanks to Titanium Backup... useless app in my opinion now that others can freeze/disable system apps. )

3. Because of the way that all of my flashing went without issue.. I never lost contacts, homescreen background, icon & widget layout, or settings. (I DID HAVE TO RE-ENABLE Developer Mode and USB debugging along with animation settings, also had to run "SD fix" again one time, but that's it.) I DIDN'T EVEN HAVE TO put my WiFi passwords back.

Ps I know most of that can be backed up and restored automatically. But I never had to bother.

NOTE: After each step following the successful flash of TWRP do yourself a favor and make a Nandroid backup to the SD. (U'll need at least 32gb to make 3 full incremental backups and still have space.) I suggest transferring them to USB or PC ASAP so that if u some how wipe the SD card U'll still have a way back.

;)

I liked CM10 on my old phone... maybe now that I've made my nandroid backups at each step along the way I have little to loose if I try a custom S5 rom now..

Anybody have any ROM suggestions, they have personally flashed on S5?

Closing thoughts:

I full owe all of my success to the wonderful community of developers here on XDA-developer forums..

Without them and their strong following of loyal users, I would never have even attempted this on my S5.

Nor would I have been able to root my wife's unrooted android 5.1.1 MetroPCS Samsung Galaxy S5.

XDA has now helped me accomplish root on more then 10 devices over the years..

Thank you XDA, & a special thanks to Chainfire, Team Win Recovery Project, Clock Work MOD (for their help with previous devices), and all the testers out there.

THANK YOU ALL..