I'm running a Chinese B508 now and I want to install B512. If I understood correctly, acoording to the file included in the official release .zip I have to be in a Bxx firmware in order to upgrade to B510 (or B512). My question is this: the bootloader in phone is locked (I check using this method) and the method decribed here to unlock it doesn't work for me. Is it necessary to have the bootloader unlocked in order to install an official firmware? If so, is there any other way to unlock it?