BEWARE, THIS WILL SET YOUR PHONE BACK TO STOCK YOU WILL LOSE ALL OF YOUR DATA
So, I was in pretty much the same situation as you are in. Here's what I did
First, Download, and install Odin 1.85 (here's a direct Download Link):
Extract it to a good location. Your Desktop will work
Next, Download the ORIGINAL Jellybean Stock Files from this thread:
(here's a direct link: https://mega.co.nz/#!WEEzSA7Z!aB4673...FBcQAZjc1X7wAE
Then, extract the files that is within the MF3 Tars file into their own seperate file.
Open up Odin 1.85
Make sure that your Phone is connected (It will be under the ID:COM, section).
Click Bootloader, and browse to the file location in which you saved the MF3 Tar Files.
Select the file named: BOOTLOADER_I337UCUAMF3_812098_REV06_user_low_ship_ MULTI_CERT.tar.md5
For PDA, use: PLATFORM_I337UCUAMF3_812098_REV06_user_low_ship_MU LTI_CERT.tar.md5
*NOTE: IT MAY FREEZE UP A LITTLE BIT. BE PATIENT!!!!
For Phone, use: MODEM_I337UCUAMF3_812098_REV06_user_low_ship_MULTI _CERT.tar.md5
For CSC, use: CSC_ATT_I337ATTAMF3_812098_REV06_user_low_ship_MUL TI_CERT.tar.md5
Then Click Start, and Hope/Pray.