G920AUCS6EQG1 AT&T Galaxy S6 SM-G920A Android 7.0 Nougat Firmware with July Security Updates

Stock firmware build version NRD90M G920AUCS6EQG1 for AT&T Galaxy S6 SM-G920A. The latter is the 4th official Android 7.0 Nougat update landed on AT&T's Galaxy S6. This build contains the July 1, 2017 Android security patches, along with general system enhancements.
Device name Galaxy S6 SM-G920A
Android version 7.0 Nougat
Android security patch level July 1, 2017
Baseband version G925AUCS6EQG1
Kernel version 3.10.61-10950877
Build number NRD90M.G920AUCS6EQG1
Release date July 25, 2017
Stock Firmware (link)

You may also check for latest firmware build release here: Galaxy S6 SM-G920A Android 7.0 Nougat Firmware

TIPS:  You may only use the most latest firmware update as it includes several system improvements and security enhancements. These includes but not limited to, such as apps and features, WiFi connectivity, signal strength,  camera, audio and video quality.

Read the Guide : How to Install Galaxy S6, S6 Edge & S6 edge+ Stock Firmware

How to Use the Stock Firmware?

Stock firmware can only be use to restore back a Galaxy S6 SM-G920A (AT&T) to the original Android operating system images if the device has been modified in unauthorized way and if the device no longer receives the OTA updates.

FOLLOW THIS GUIDE: Install Galaxy S6, S6 edge, and S6 edge+ Factory Stock Firmware

1. Backup all important data stored in the device memory, including contacts, messages, photos, videos, music, and other files.
2. Recharge the phone or it should still have at-least around 50% remaining power.
3. Grab these tools:
– Odin3_v3.12.103 (Nougat)
– Odin3_v3.11.1 (Marshmallow)
– USB driver or grab Smart Switch

4. Extract the firmware package in your PC.
5. Open or run Odin3 in your computer.
6. Reboot the Galaxy S6 in Download mode. Turn Off the phone then press and hold down the Volume Down+Power+Home keys at the same time. You may then press the Volume Up key to continue.
7. Connect the phone to PC.
8. Load the stock firmware:
a. Single tarball – Click on AP button and load the stock firmware tarball.
b. Multiple tarball – Load each individual stock firmware tarball such as BootloaderAPCP, and CSC on Odin3’s designated slots.
9. Click the “Start” button to begin the installation.
10. Wait until the flashing completely finishes and the phone reboot itself.

You may also do perform a full factory data reset to regain a cleaner and fresher firmware installation. Just ensure that you already made a backup all of your important data stored in the phone.