[OnePlus 10T 5G] beatbreakee:
(Moderators, please make this post a sticky, and i will keep it updated of any changes or issues that might come up in future builds, thanks)

To clarify things.... I am the dude who figured out how to side-step from model to model... I have went from 2419 (android 12 .11), to 2413 (android 13), Down to 2415 (android 12 .08), then 2417 (android 12.10), back up to 2415 (android 13), down to 2415 (android 12 .05), 2417 (android 12 .08) and finally a FULL sidestep 2417 (12 .08) to 2415 (12.08) which the latter is supposed to be impossible, with downgrade package, yet i am sitting here and i have done it!

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The END result of each region swap will be your device FULLY IDENTIFYING as the model for that region.. (ex. 2419 will now show as 2415 if Global, 2413 if India, or 2417 if North America)

This will change EVERY TIME you flash a different region, and Local Updater will block you from flashing if it detects a lower build, EXCEPT for the 2415 Downgrade Package. So ALWAYS use that as a base if you want to go to another region. <ie. to go from 2413 to 2417, i recommend first flashing the 2415 downgrade, which will put you on A.08 build, then you can update to any region you want, even the Android 13 builds.... but if you want to go to a different region and back to 12, you must use that 2415 Downgrade or Local updater will stop you. The 2415 is a signed official rollback package direct from oneplus, so it allows you to downgrade from pretty much any version.

***** KEY FACT ***** This ONLY applies to OTA upgrade and downgrade packages that come in a single zip file that contains 3 items. Payload.bin Payload_properties.txt and Meta_Inf folder ... If you unzip the fw that you dl, and it contains anything other than those 3 that i just named, you either have a Fastboot package, a Full system package, or a MODIFIED package which you should NOT interact with unless you completely trust the source it was dl from. I have seen some NAAAAASTY scripts, coded in Russian, Vietnamese, Chinese, and Wingdings (yes that weird windows font!) ... and they are becoming VERY GOOD at moving to an app directory, changing a files name and replacing that file with WHATEVER IT IS, but renamed to a something common to the location! So by doing that, those files evade most onboard detection, if they have modified code, because that file name was whitelisted . Stick with the signed rollback package, and OTA either direct from the Oneplus community websire, or from the "gsmmafia" site, as both are packages sourced direct from the manufacturer and contain no modified code!

***How to get the OTA files for the region you want to switch to... follow instructions EXACTLY and you wont have an error.***

You have to use the "OXYGEN UPDATER" app from the google play store... When you first open it , it will tell you that your device is on the current version... ignore that, and you have to open the settings menu for it, and go enable ADVANCED MODE.... This will allow you to go back and CHOOSE what device you are supposedly using. (kinda a cheap override command)... doing this will let you choose the 2417 (NA) model. **Now once again HIGHLY IMPORTANT that you are doing this ONLY after flashing the Downgrade/Rollback so that you will be on 2415 A.08 build... cuz then when you select the 2417 model, it will show an update available for 2417 A.12 build. and also the Android 13 Beta. Pick whichever you want, and click download... NOW once downloaded DO NOT HIT THE REBOOT BUTTON.... this will attempt to flash it via normal methods... instead jump into ADB , go to Shell, and head to /sdcard/ and start looking for the folder where it just downloaded the update. It places it sometimes in the main /Sdcard/ folder, and other times in the /Sdcard/Android/Data/<app name>/ folder.... you will know it when u see it. Find it and copy it to your computer and then you have the official OTA saved. After that, make sure it is moved to the /Sdcard/ folder and use "local updater". Will ask you to confirm, click Ok, and it should start the verification and flash process.

Be advised it will APPEAR like its frozen or no progress for like 4 minutes, then it will slowly start moving. Once it gets to 99, it will appear stuck again... just be patient and about 5 min later it will complete. Total flash time is arouund 20-25 min.

DO NOT FORGET TO UNPACK THE ZIP FILE

EDIT THE PAYLOAD_PROPERTIES.TXT

CHANGE THE "0" TO A "1" ON THE ENGINE_UPDATE_CHECK_DISABLE =

SAVE THE CHANGES, AND RE - ZIP THE CONTENTS

THEN COPY THIS ZIP FILE TO YOUR /SDCARD/ FOLDER!

if you dont it will fail!

Links to Downgrader Packages used can be found HERE

👇👆EDIT: I went ahead and linked the main files necessary for this whole process here for ease, and my peace of mind. Now I know that you have all re required tools. Enjoy!

2015 Rollback Package, courtesy of EtherealRemnant

Oxygen Updater (for current OTA of region)

Local Update apk (official)