To explain, I got a used AT&T S5 SM-G900A which I tried to root using Odin software, I successfully flashed an older version of Android on to my phone which was 4.4.2 but then it caused the phone to go into a boot loop. Any subsequent attempts have resulted in failure to override the system. I tried using Samsung keis emergency firmware to fix the problem, but the software could not recognize my phone which was odd considering Odin could ID my phone where kies could not. I tried as a last resort going to an AT&T store to try and get them to fix it only to be told 'we can't do anything'. I'm out of options voat, any and all help would be greatly appreciated.