New Samsung Galaxy S8, S8+, and Note8 Bootloader Prevents Flashing Out of Region Firmware
Samsung is rolling out a new update for the Galaxy Note8. These updates come with the January security update which brings some patches for the Spectre and Meltdown vulnerabilities, but it also comes with a new bootloader. An update bringing a new bootloader on Samsung phones means that you can not downgrade your phone after installing this. This new bootloader also has one more nasty secret: it patches the use of Prince Comsy’s modded Odin.
Odin is a Samsung tool used to flash and install new firmware. When Samsung builds Android, they remove some features like fastboot from the bootloader, and instead replace it with Odin. The Odin tool that we have is leaked from Samsung and it works on all modern Samsung phones, but can only flash to devices with matching model numbers. That’s where Prince Comsy’s modded Odin comes in. Prince Comsy’s tool is a version of Odin modded to support flashing versions of Samsung software not signed by Samsung or firmware signed by Samsung but for a different region with the same SoC.
Since Prince Comsy Odin no longer works with this new bootloader, that means that any builds that are not officially signed by Samsung will not flash. This also means that if you have a Canadian phone and want to flash the U.S. firmware, you can no longer do so. This is because even though they are signed by Samsung, the model numbers do not match. Unfortunately that also means Note8 owners with the carrier Note8 devices cannot flash the US unlocked firmware. If you try to flash the carrier unlocked firmware on carrier phone, it will hard brick your phone. Currently, there is no way to restore from a hard brick in Odin from the new bootloader.
If you are on the US unlocked firmware and update to the new bootloader when it is released, you should still be able to get back to a carrier build, but we won’t be able to test this until the release of a US unlocked firmware build with the new bootloader.
Although US carriers just released the new bootloader builds today, Exynos Note8’s started to receive the January update just a few weeks ago. These come with the same patches to the bootloader that patched Prince Cosmy’s modded Odin. Official signed builds will still work for flashing, though.
Even though the new update has rolled out to the Note8, the Samsung Galaxy S8 and Galaxy S8+ have yet to receive it. However, on the Android Oreo beta, the included bootloader has the same changes made. The reason flashing through Prince Comsy Odin still works is because the bootloader has not been fused, which means that the efuse on the motherboard has been incriminated and will not allow any program to downgrade it. Once these builds get the new BLv3 revision, it will be permanent and will not be downgradable so for Galaxy S8 users, this will have the same effect in patching root methods and flashing changes.
EDIT: After being tested by XDA Senior member me2151, it turns out cross region flashing does work. Prince Comsy Odin is working, but we can not test if the factory binary flashing will hard brick your phone. So flashing US unlocked onto a US carrier device should work.