Just bought a Samsung S21 Ultra but its a Korean model so I have tried to change my Operating System from the Korean version to the South African version but I am getting Security Check Fail (PIT) Error. I have tried unlocking bootloader and downloaded different flash files but none of these things worked except for the Korean Flash file only.
Never unlock the bootloader except when very necessary. Once unlocked, the warranty is void, and apps that depend on Knox security will not work properly or not work at all. Maybe you tried to install a lower version of the software.
