Originally Posted by marty136
You can't downgrade once you've installed 4.3 because of new bootloader and knox that was installed with it, I have been to heaven and hell to downgrade mine because i was having big problems with T999VVLUEMK5 but after hardbricking mine trying to do so, i de-hardbricked it with a debrick image 4.3 created by a xda member here, i successfully installed the new T999VVLUEML2 and now phone works perfectly. So people who say it is easy to downgrade from the locked 4.3 bootloader must be very good cause i sent mine to repair shop and they said it was impossible at the time(mid december 2013).
My two cents
Seems like I have no choice but to pay for the unlock. So with 4.3 and the new bootloader which includes the KNOX protection, downgrading is pretty much a bitch eh. So in the end how did you managed to downgrade it? If you did in the end that is...
Originally Posted by Perseus71
I believe he's trying to downgrade the Baseband AKA Modem. I don't think he wants to downgrade the Bootloader. Unfortunately both are identically named so easy to confuse.
I'm guessing the 4.3 official OTA update updates the bootloader and firmware as well and the new bootloader doesn't support basebands from earlier builds? Not too sure, making a random guess here.