i can confirm that unlocking the bootloader doesnt work on B221!
the first error i got at starting the prog on win7 x64, it always cried around cuz it didnt find unlock.bat at Temp folder,but no problem - i extracted the prog with winrar, so i got a folder with all files in it (e.g.: adb.exe, fastboot.exe, twrp.img, etc.). than i ren cmd out of the folder, after flashing everything the fastboot oem get-bootinfo says this:
OKAY [ 0.565s]
finished. total time: 0.566s
i think i´d have to downgrade to B907, to get the bootloader unlocked, right? is it hard to downgrade? or np?
but, i also have read in another forum that the bootloader of the ham mt1-u06 shouldnt be locked from stock, looks like this is just an incorrect information as we can c.