Galaxy S3 stuck in infinite "recovery boot" while updating, help?

about an hour ago i went to update my AT&T Galaxy S3 (current phone broke, its my backup) and i havent used it in a very long time, so obviously there are some updates required. as i was getting the updates i was prompted to restart my device, so i did. now my phone is stuck in a loop of "recovery boot" and update install.. first it will bring up the samsung logo with blue "recovery boot" at the top, then it will show the "samsung galaxy sIII" words on the next screen, the third screen is the AT&T logo and the update progress bar at the bottom. every time it gets to 100%, the process starts all over again.. ive tried every boot method out there, and nothing is working! i hope someone can help me out or point me to a subreddit that can (i thought it would be appropriate here)

Edit: when the update gets to around 90-95% it says "update failed", this is probably the cause of the loop, am i wrong?