If you got stuck (boot loop) at the ATT Logo,

1- remove the battery

2- then hold volume up/down and power button at the same time

3- when the Samsung logo appears

4- release the power button while holding the volumes. 

5- You will enter the Android System Recover, select Wipe data/factory reset and wipe cache partition. 

This works for me

I take no credit for this, I readit in this thread.