SM-G900A firmware corrupted

Hi, i recently got the SM-G900A from AT&T and the firmware corrupted. It was running stock lollipop with the build number G900AUCU4BOF3. At first i was on a screen where it said for me to "Connect to Kies and select Emergency Recover" or something, but my phone isn't supported nor does it show up on Kies. I have tried every stock version i could find to try and downgrade my build number if possible, but it would always fail in Odin.

Also, in Recovery Mode it shows a completely different build number: G900AUCU1ANCE


<ID:0/009> Added!!
<OSM> Enter CS for MD5..
<OSM> Binary Check MD5.. Do not unplug the cable..
<OSM> Please wait..
<OSM> Checking MD5 finished Sucessfully..
<OSM> Leave CS..
<ID:0/009> Odin engine v(ID:3.1100)..
<ID:0/009> File analysis..
<ID:0/009> SetupConnection..
<ID:0/009> Initialzation..
<ID:0/009> Get PIT for mapping..
<ID:0/009> Firmware update start..
<ID:0/009> SingleDownload.
<ID:0/009> aboot.mbn
<ID:0/009> NAND Write Start!!
<ID:0/009> FAIL! (Auth)
<ID:0/009>
<ID:0/009> Complete(Write) operation failed.
<OSM> All threads completed. (succeed 0 / failed 1)

The thing i don't really get is why it let me flash "system.img.tar" and it won't flash a full stock rom without the output above.. Any help would be greatly appreciated! If possible, can someone dump their stock rom?