Uploading a stock backup for TWRP 188.8.131.52 ... you'll need to have this exact recovery for this to work.. tested on my and my girlfriends L720t..
Okay this will take a minute to upload on my end. And your end will take a while to download. Try to be on Wi-Fi.. I know this may not be very easy if you don't have in home Wi-Fi.. lol
After I get you a link.. and you make sure your recovery is TWRP 184.108.40.206 make a backup of just one small partition(making the folders for us to follow).. like cache then reboot and go to a root file explorer.. like root browser or es file explorer. And copy/paste the whole file/folders I'm uploading in sdcard/TWRP/backups. Right next to the one you backed up.
Reboot back to TWRP and go to restore menu. Make sure the backup is there and restorable.. do a wipe of everything except internal storage.
Flashing may cause some slight fc's.. (force closes) this is to be expected.. it may even prevent you from singing in.. still try.. have patients.. if you can't at all.. (like the keyboard itself is fc-ing) do a battery pull and boot recovery. Wipe davlic and cache. Try again. It should still give problems.. but stable enough to sign in to gmail. Afterwards.. go directly to sprint zone.
(In this order) update prl, then firmware then software. (If not on NC6 this will update you to NC6 4.4.2)
Again go through the updates. And reboot.
Let google do its thing.. and your all set. Stock rooted and you can back this up as your own and get rid of mine.. lol
@Jackroo .. this files kinda large.. so give me awhile to upload. K