There's always a boot sector in reserved sectors, that's how FAT works. You should try NxNandManager to re-format USER, it'll recreate boot & info sectors with
original values (as much as possible).
About your BitLocker tag problem, maybe there's a value somewhere in info sector that describes partition's encryption mode. USER, SYSTEM, SAFE, PRODINFO & PRODINFOF are all encrypted with AES-XTS mode (decryption uses BIS keys), BitLocker uses AES-XTS too, if I remind correctly. I guess that's why Windows labels your partition "BitLocker" even though it's not encrypted with BitLocker.