[AT&T Samsung Galaxy S8+ Guides, News, & Discussion] sean8102:
Hey guys I just got done flashing the G955USQU5DSC1 Android Pie Firmware that Sprint released for the S8/S8+ (and Note 8). The steps are below if you want to do it It's your risk and since we just had the first US carrier push the Pie update the others should be close behind but if you want it now this works perfectly. At least it did for me and for a few others I saw on reddit. I was able to do so without wiping my phone either, no data loss at all. Everything is working perfect, AT&T bootscreen, Wi-Fi calling, VOLTE etc.

Step 1: First off download and install the Samsung USB Drivers for Mobile Phones https://developer.samsung.com/galaxy/others/android-usb-driver-for-windows if you don't have them installed already (reboot after installing them) Use "SamFirm" to download the Sprint Firmware (no throttled download speed like most sites etc) I used v0.3.6 https://bit.ly/2Gso6QQ

Step 2: Launch "SamFirm" (I set the Auto/Manual check box to Auto) and input your model number (Settings>About Phone) or SM-G950U for S8 and SM-G955U for S8+

Step 3: In the "Region" field of "SamFirm" application put in "SPR" for Sprint, and click "Check Update". When you're ready to download it should look like this (G-950U for S8 instead of S8+) When you click download it will ask where to save the Firmware, I just saved to my Downloads folder.

[IMG="SamFirm Download Ready (S8+)"]https://i.imgur.com/iTM45Ja.png[/IMG]

Step 4: Once the Firmware download and decryption process is complete you can close "SamFirm". Go to where you told the app to download the firmware, right click it and click extract. Now it's time to use ODIN. At this point if you just want to be extra safe I would use Samsung SmartSwitch app on your phone to create a backup of your phone either to your MicroSD card (easiest) or to your PC. This will backup App /w app data, home screen layout, settings, documents, music (not needed if on your SD card) etc. But I didn't loose any data or have a reset when I did this.

Step 5: Download and open ODIN, I used ODIN 3 v3.13.1. Do the usual of clicking BL/AP/CP etc. then point ODIN to that file of the Firmware that is inside the folder you extracted (ODIN will take a second to scan each file as you add it, just wait for it to finish). For CSC make sure you select CSC do NOT select HOME CSC. If you select HOME CSC it will wipe your data/reset your phone. Also do not select the USERDATA file. Leave USERDATA blank in ODIN (at least for AT&T and Verizon users who this guide is for).

[IMG="ODIN ready to go"]https://i.imgur.com/Vigv2yA.png[/IMG]

Step 6: Boot your device into download mode. Power off your S8/S8+, then press power and hold power, volume down, and bixby button at the same time. You should very quickly get a blue screen, release the buttons. The screen will say press volume up to continue, do so. Now plug your S8/S8+ into your PC. ODIN should show a blue square under ID:COM like in the previous photo. If ODIN looks the same as my screen shot while you're in Download mode you're ready to go. Now just hit start and wait for the process to complete fully. When it dose finish your phone will reboot and ODIN will show a green square with the word "PASS".

[IMG="Flash successfull"]https://i.imgur.com/5QSzrn2.png[/IMG]

It may take a bit longer than normal for your phone to boot this first time. Also the first time my S8+ rebooted I wound up in the recovery menu, but simply hit the power button since the first selected item is "reboot phone" and the power button is the select button. If you get some white text at the bottom saying its doing something just wait for it to finish and when you get the reboot option hit the power button. That's it. After that my S8+ booted up just fine (this boot may be a bit longer as well but only this time) and I was at the lock screen. All my apps still installed, settings the same etc etc. Just like getting the update OTA.