Sounds like bad firmware update from AT&T. I don't know if you can "roll-back" to your old firmware. Were you able to get into recovery mode? If you can eventually factory reset / restore, AT&T may force you to download the bad firmware again. Check online to see if other AT&T users are getting this same issue. If so, you may want to try to wait till they fix the firmware/issue.

Make sure you have backups!!!!!