I have spent the better part of the evening trying to figure out what is wrong with the full update package for Android 12 for NA/Global. This is the one way out of the many I tried, that reliably worked for the KB2007 T-Mobile USA device to get it to running Android 12 without issues on the North American/Global firmware.
This ideally is for those of us that have a KB2007 that used the MSM Tool conversion to the EU firmware. Using Local Update does not fully convert to the NA/Global, even when using a full update package, which leaves the device with issues. For some reason, when updating to the KB2005 Android 12 using the full firmware image, you lose the second SIM slot, which just makes it worse. After plenty of flashes to figure this out. I have figured out a complicated mess of a way to do so.
I tried going to a couple of the full updates before Android 12 from the EU and still had issues after the update to Android 12 with performance. That is why I decided upon this longer method. Update using the full KB2005 image to Android 12. Easiest place to get it is from Oxygen Updater. Install it via Local Update. Download the rollback app, install it, and download the rollback package to flash through the rollback app. Rolling back to KB2005 using the downgrade image returns dual-SIM to the KB2007. That will have wiped your device so proceed through the setup until finished. Download Oxygen Updater again, download the stable KB2005 Android 12 incremental update through the System Updater, install it, and you should be as close what a KB2007 can get to a KB2005. I tried the full package update but that always disables dual-SIM after updating to Android 12, whether you do a factory reset before the flash and after or not.
Having an MSM Took to directly convert the KB2007 to KB2005 might have made this somewhat easier.
This ideally is for those of us that have a KB2007 that used the MSM Tool conversion to the EU firmware. Using Local Update does not fully convert to the NA/Global, even when using a full update package, which leaves the device with issues. For some reason, when updating to the KB2005 Android 12 using the full firmware image, you lose the second SIM slot, which just makes it worse. After plenty of flashes to figure this out. I have figured out a complicated mess of a way to do so.
I tried going to a couple of the full updates before Android 12 from the EU and still had issues after the update to Android 12 with performance. That is why I decided upon this longer method. Update using the full KB2005 image to Android 12. Easiest place to get it is from Oxygen Updater. Install it via Local Update. Download the rollback app, install it, and download the rollback package to flash through the rollback app. Rolling back to KB2005 using the downgrade image returns dual-SIM to the KB2007. That will have wiped your device so proceed through the setup until finished. Download Oxygen Updater again, download the stable KB2005 Android 12 incremental update through the System Updater, install it, and you should be as close what a KB2007 can get to a KB2005. I tried the full package update but that always disables dual-SIM after updating to Android 12, whether you do a factory reset before the flash and after or not.
Having an MSM Took to directly convert the KB2007 to KB2005 might have made this somewhat easier.