The latest N910VVRU2BOG5 bootloader is incremented; i.e., if you take the OTA or flash the official firmware via Odin, you won't be able to downgrade.
For Retail Edition: This is very important if you want to gain ROOT access when available & keep it over OTAs then.
For Developer Edition: If the bootloader is incremented with any coming OTA, it'll block your unlocked bootloader for good & you'll end up with a Retail Edition.
Safe upgrade allows you to downgrade to any previous firmware (KK or LP)...
- Extract the N910VVRU2BOG5_StockRestore.tar.md5 file using 7-Zip
- Extract Odin v3.10.7 & open it
- Reboot to Download Mode (press and hold Home + Power + Volume Down)
- Connect phone and wait until you get a blue sign in Odin
- Add the N910VVRU2BOG5_StockRestore.tar.md5 file to AP / PDA
- Make sure re-partition is NOT ticked
- Click the start button, sit back & wait a few minutes
- Reboot into recovery (press and hold Home + Power + Volume Up)
- Wipe data (Factory Reset)
- Reboot to system