[Cesar Castillo]

can someone help me fix this problem

[joe.kent]

Just download Odin and the factory firmware, follow the steps and in about 20 minutes you'll be back up and running.

[Cesar Castillo]

not work bro i try da before i get a message saying fail

[knighthawk321]

The AT&T S4 has a locked bootloader. If you took the latest OTA, the current root methods got closed off. No Odin, no Loki. If you're in that boat, you're stuck with stock ROM until a new crack is discovered. The way to tell is to look at your baseband version. If the last three characters are MF3, you're locked up for now. If you have MDL or previous, you can achieve root. I'm rooted, and working with my Developer friend to break this puppy wide open. Right now I'm in modified rooted stock.

[markbc]

There seem to be several XDA threads where folks have had this problem. Some appear to have recovered. (not sure if they were on UCUAMDL or UCUAMF3) but it is worth checking that out -sorry if you already have been there! Here is just one of them

[Q] Help!!! System software not authorized by ATT has been found on your phone - xda-developers

Good Luck!

[Cesar Castillo]

i understand but i never root or hack this p hone in any way i was making an update and this happend -__-

[markbc]

- Right, I am sorry to read that it happened -and I am sure it is very frustrating in any case. :-(

- That is a weird and unfriendly Samsung message! Scanning the XDA threads it seems that in many cases this message occurs when the wrong kernel is applied.

- Regardless on how you got here, I think your best bet is to try and follow the instructions or guidance that you find on XDA for threads by others who have experienced the same problem. (You also could google "software not authorized by AT&T," but most of the hits will lead you back to XDA answers and their efforts to root and restore the phone.
(This phone actually roots easily -as long as you are not updated to UCUAMF3. So if you have not been updated you have a chance of fixing this yourself!

- If you can't fix it yourself, you may have to go back to the dealership and see how it works out ;-((
(that is really a last resort that I would seek to avoid, btw)

Sorry I can't be more helpful, but I do wish you good luck!