[Q] Need serious help to safely restore i337 to stock everything

I received a new phone since I broke my old GS4 (I337). It was on AT&T 4.2.2 and I rooted it using motochopper. It was fine. It automatically updated while I was asleep to 4.4.2. I had rooted my old GS4 on the same update. So I figured I'll just root it again. So I used the method where I flash the NC1 kernel, use towel root, then flash NJ4 back. Now my WiFi will not turn on, but I do have root access. Also, a message saying "Unauthorized actions have been detected" and it tells me to restart to undo these changes. I don't want to do it in fear of bricking my device. I'm really scared now and I desperately need to fix this. I just want to go back to complete stock 4.4.2. I've tried reflashing the NJ4 file twice and WiFi will still not turn on. I've attached pictures of the notice and my device info. Please help. I cannot brick this device. I will answer to any questions as fast as possible. At the moment, I am debating whether or not to flash this because I am unsure if it will be compatible. ALL_ATT_I337UCUFNB1_I337ATTFNB1_505595_REV06_user_ low_ship_MULTI_CERT.tar
http ://i.imgur.com/68B7MNM. png?1
http ://i.imgur.com/6Cjnzug. png?1