Samsung Galaxy S3 stuck in boot-loop before it reaches recovery mode?

A

AC Question

I rooted my new Galaxy S3. Shortly after that I got an automatic software update which sent the phone into a boot-loop. The update gets to 94% before failing, restarting the phone, and restarting the update.

I have tried getting the phone into recovery mode but before I can get any menu options the Samsung Galaxy SIII screen appears and the update starts (and fails) again, restarting the boot-loop. I can get into download mode but I don't know what to do from there.

After some research it seems I can flash the update with a program called Odin. Is this safe to do? I would rather factory reset my phone than risk bricking it, but I can't get into recovery mode before the update starts again. Any ideas would be much appreciated. Let me know if you need more details. I have the SGH 1747 model, LTE ATT Galaxy S3, American region. Thanks again.