1. Take the NI1 OTA update. (Should the update fail see troubleshooting section below).
2. Place your phone into “Download Mode” (press and hold the “Home”, “Volume Down”, and “Power” keys until the phone powers on and displays warning screen, then press “Volume Up” key).
*3. Flash the I337_NC1_Stock_Kernel using Odin’s PDA slot(AP in Odin v3.09+).
4. Root using Towelroot-v3.apk(internet access not required).
5. Power off then boot into “Download Mode” again.
6. Flash the I337_NI1_Stock_Kernel also in Odin’s PDA slot(AP in Odin v3.09+). Done!
*Note: After flashing the NC1 kernel your phone may run a little wonky, e.g. extreme lag, no wifi, etc., and towelroot may not root on the first try. If that happens reboot and re-try towelroot. Once rooted and after flashing the NI1 kernel your phone will once again run like a champ!
Important!: Do not skip any of the above steps or you may experience issues with your device.
Troubleshooting – Should the NI1 ota update fail consider one of the following options:
Option 1: Consider flashing back to stock NB1 using either file in this thread: I337UCUFNB1 4.4 Stock Odin Tars & System Dump. Then taking the NI1 ota update or place the I337_NB1toNI1_OTA_Update.zip onto your ext-sdcard and sideload from stock recovery. Once updated to NI1 continue from Step 2 above.
Option 2 – For Safestrap users: a. Place the I337UCUFNI1_100%_Stock_Rooted_ROM.zip onto your ext-sdcard. b. Reboot into Safestrap recovery then perform an “Advanced Wipe” and wipe everything but your ext-sdcard. c. Flash the I337UCUFNI1_100%_Stock_Rooted_ROM.zip using “Stock Slot.” d. Once complete press “Home” then reboot into “Download Mode.” e. Flash the I337_NI1_Stock_Kernel in Odin’s PDA slot (AP in Odin v3.09+). Done!