[Samsung Galaxy Note 20 Ultra Guides, News, & Discu] k24a1:
Introduction​

So... I was genuinely thinking of selling my Note 20 Ultra after the numerous headaches that OneUI 4 gave me, and then I thought "Would a reset fix my issues? What if I could go back to 3.1?"

And my venture began. I referred to the OTA/firmware thread in this forum along with flashing a U to a U1 (which I did, because carrier bloatware sickens me...) and I went to download the latest version of Android 11 they made... which luckily still flashes since we're still on Bootloader version 2. So I'm putting together this hastily made guide so you can downgrade to Android 11, AND prevent software updates.

Precautions​

1. Make sure you back up everything. Don't put the blame on me if you lose your baby shower photos simply because you forgot to back up. Also back up your call logs, messages, app data, etc etc. This step is optional if you don't care about whatever you possibly even have on your phone. I am also not responsible for anyone who damages, bricks, or outright fries their glass slate (aka the Note20 Ultra in this case) during the process. Your phone, your decisions. The only thing I did was write this guide.

2. Be sure you're on bootloader 2, which you'll be able to identify through download mode. I think it's BL or something, I forgot. But it has a 2 in it.

3. Be sure your stuff works well enough to the point where nothing bad happens during the flashing process. You don't want to be using an unstable computer for this kind of stuff... trust me.

4. Speaking of computers... you need a windows machine (Windows 7 or later) with a patched version of Odin, and samsung's USB drivers. Oh, and how could I forget... a USB cable! More specifically, a USB-C or a USB-C to A cable.

5. For firmware, refer to this thread. Some links might not work because AFH can't find a suitable mirror, so google the firmware version and you might be able to find another download for it somewhere. In this case, here is the latest Android 11 for the XAA CSC (US unlocked). galaxyfirmware.com has other CSCs for the latest patch, just use the direct link.

6. Be sure you find the right firmware for your CSC, unless you want to flash unlocked or another carrier's firmware. This thread goes into good detail about it. I was able to flash my N986U to an N986U1 and it works perfectly.

7. Follow directions and don't skip any of them.

Alright... let's get to it.​

First things first, reset your phone through settings to clear any locks and to be able to set it up offline. This also lets odin do its thing. Odin will NOT work on FRP locked devices, and I am not allowed to share how FRP locks can be bypassed. Don't steal devices, kids.

Now... the rest is actually fairly straightforward! It's almost like this post was absolutely pointless, right? Well, sorta. You still need the Patched Odin (and I mean patched, regular odin won't work) to do the rest. You also need to find the right firmware for your CSC (which is simple if you have a snapdragon, because you most likely live in the states if you do) and the links in the precautions section talk about a lot of this already. Examples... TMB is T-Mobile, ATT is AT&T (in which I feel sorry for you), VZW is Verizon Wireless, SPR is Sprint, XAA is US unlocked, and so on...

So now you want to download the correct firmware file after you've done your research, and in this case it will either be the November or December 2021 security patch. January 2022 patches are Android 12, and that's not what we're here for. Of course, you could downgrade to an older Android 12 firmware, but we're focusing on 11 here. Long story short, anything still on bootloader 2 will work. Down the line they're probably gonna update it, but luckily the latest Android 12 still runs BL 2.

Alright, now is when I'll shut up about firmware files and bootloaders. Once your device has been factory reset through the phone and NOT through recovery mode... restart your phone and enter download mode (hold both volume buttons after you press "restart") and you'll see a screen that says that loading a custom ROM will damage your phone blablabla, ignore that and go ahead. We're flashing official firmware, and official firmware only. No, this will not trip knox.

You want to start loading your BL, AP, CP, and CSC files into Odin. Now is the time where you make sure everything you did beforehand worked, and you have a proper backup of your phone's data. Hit start, and let the magic begin.

And that's about it! for the most part... you still need to disable updates.

Set your phone up OFFLINE (so sammy doesn't shove an update prompt into your face, also remove your SIM card) and enable Developer options. Disable auto-updates and enable USB debugging. Assuming you have the 15-second ADB package or other ADB environment already installed, open up an adb shell by literally typing "adb shell" into an admin command prompt. If you don't see an authorization prompt on your device, set your USB connection mode to "transferring images" on your phone. Then it should pop up.

Now, type in this string of commands:

pm uninstall --user 0 com.wssyncml

pm uninstall --user 0 com.sec.android.soagent

exit

and Voila! Now you're back on Android 11, and you won't have to deal with updates.

If by chance you do want to embrace masochism I mean, re-enable updates...

adb shell cmd package install-existing com.wssyncml

adb shell cmd package install-existing com.sec.android.soagent

Now you'll start having OTA updates again.

Potential issues​

Backups made through Smart Switch or Samsung cloud might not work with Android 12. I usually back up to my computer by copying the contents of my internal storage+SD card, and I just start anew. Personally, my Android 12 install was pretty trashed.

Things that rely on Android 12 obviously won't work on 11, but I know of NOTHING that requires Android 12 at the moment... yet.

Again, we only have so much time before Samsung updates the bootloader again. Inform me if they do... I usually don't keep up with all of that.

Other than that, everything still works great. No tethered crap too, we're not dealing with iPhones.... although I wish they could allow us to downgrade THOSE.

Questions you may or may not have​

Q: That's cool, ma'am, but can you downgrade to Android 10?

A: Unfortunately not... that's what I was initially going for. Android 10 doesn't have the same bootloader version.

Q: Will this make my device faster, and will it remove that god-awful scroll stretch effect?

A: Yep.

Q: Will this break anything on the phone?

A: No, not even Knox. It's completely safe.

Q: What if the bootloader does get updated?

A: Any firmware you'll be able to flash now would need to have the same BL version as the latest firmware.

Q: My computer does not detect the device, even with drivers installed.

A: Your USB cord might be bad, or the port you're using is either bad or potentially unsupported.

Q: Does this work on Linux?

A: I'm sure it will but I have no idea how to work a damn thing on Linux without it breaking.

Q: Will this work on Exynos devices?

A: Yes, provided you have the right firmware. This should work on all Note 20s.

Q: What if my device was produced after 2021?

A: This may or may not work for you, then...

Any other questions go in the replies. I'll shut up now.