[Samsung Galaxy S21 Ultra] FrozenCrunch:
Hey all,

I'm writing this because I hope it'll help someone else who needs it. I have a VZW-branded S21 Ultra. I previously flashed it to the unlocked non-carrier firmware, but after having to get it serviced and ending up with a phone that had the latest Android 12 VZW ROM flashed to it, I wanted to go back to the unlocked ROM (and I'll let the OTA take care of the upgrade to Android 12). By the time you read this, the Android 12 OTA may already be present. If you

This will only let you take any carrier-branded S21 Ultra and put the non-carrier-branded global ROM on it. It will not unlock your phone, it will not unlock your bootloader, it will not trip KNOX (because it's an official image). I recommend using the standard CSC as well (and not the HOME CSC). Just do it clean.

Here's exactly what I did:

We need the firmware file itself. We can use Frija to grab the firmware without having to go through places like SamMobile. Grab Frija from here: https://xdaforums.com/t/tool-frija-samsung-firmware-downloader-checker.3910594/.

In order for you to be able to run Frija, we need two C++ Redist executable installed. You need to install both the x86 C++ Redist 2008 (Link, be sure to grab vcredist_x86.exe, not the x64) and x86 C++ Redist 2010 (Link, again, be sure to grab vcredist_x86.exe, not the x64). Install them both. You do not need to reboot after installing.

Open up Frija (if you didn't install the above Redist files, you'll get an error). Under the model, enter SM-G998U1. For the CSC, enter XAA (unlocked non-carrier variant). Click on Check Update and then save file, and let it run. Once it downloads, it will then decrypt the file into a zip. This will take some time depending on your connection.

When it finishes downloading (by default, it saves the zip file to your Documents folder), find the zip file, right click on it, and Extract All. Let it finish fully extracting.

Now, we need a patched copy of ODIN. The reason we need a patched copy is because by default, ODIN will detect you're trying to flash an XAA (unlocked non-carrier) ROM to a VZW (or other carrier-branded) phone. The patched versions bypass this check. From this page, grab the Odin3 v3.14.1_3B_PatcheD.zip file.

Unzip the Odin3 v3.14.1_3B_PatcheD.zip file, and run Odin as Administrator.

Click on the BL button, and then navigate to the extracted firmware folder, and select the only file that starts with BL. Give it a few seconds to finish loading the file.

Skip the AP button for now (you'l understand why in a second), and instead click on the CP button. Navigate to the extracted firmware folder, and select the only file that starts with CP. Again, give it a few seconds to finish.

Click on the CSC file, and then navigate to the extracted firmware folder, and select the only file that starts with CSC. Give it a few seconds to finish loading the file.

Finally, click on the AP button, and navigate to the extracted firmware folder, and select the only file that starts with AP. This will be the largest file in the firmware folder, and coincidentally, will take the longest for Odin to finish loading. It may seem unresponsive, it may look like its frozen, do not touch anything. After a few minutes, it will finish.

Put your phone in Download Mode. The most reliable way I've found for doing this is to turn the phone completely off, wait a few seconds, then hold both Volume Up and Volume Down, and then plug the USB cable from your computer in to the phjone. Don't let go of either volume button until you see the blue screen. Press Volume Up once to enter Download Mode. In Odin, you should now see "COM1" in the top left-most box, and the log window should say "Added". This is good.

Click Start. It will most likely get to the point where it says "SetupConnection" and then appear to get stuck (on successful runs, it should only pause here for a second or two at most, any longer than that, and it's stuck). To get around this:

Do not close Odin.

Unplug your phone.

Press and hold Power and Volume Down for 7 seconds to reboot the phone.

If it powers all the way back up, power it back down. If it powers into recovery, select the Power Off option and power it down.

Once more, hold both volume buttons, and plug the USB cable back in to enter Download Mode.

Click Start once more, and this time, it will get past the "SetupConnection" message and continue on to flash your phone. Wait until it finishes completely.

If you left the checkbox for "Auto Reboot" checked the phone will reboot on its own once you finish flashing the firmware. If you unchecked this box, you'll need to manually reboot the phone.

Your phone is now flashed. Congrats!'

If you were struggling with figuring this out, I hope this helps.