MR1100 att firmware issue

Have a MR1100ATT that has corrupt firmware.  Does anyone know where I can download the ATT firmware and flash the MR1100 with the new file?

If not, will the unlocking of the MR1100 allow me to use the netgear firmware available for download?

ATT Customer service was no help as the MR1100 shows that the firmware is up to date

Thanks