Only FastBoot can enter, bootloader locked.need unlock file to update

  • hello!
    my U2 was 1.9.0
    I try to updating the firmware to 1.10.0 And above
    But all failed
    Yesterday, I tried again to update firmware. 
    Unfortunately, the phone couldn't start. Only FastBoot can enter, but bootloader locked.
    The Flash Tool also told me i need unlocking file
    Otherwise, I will not be able to update my firmware
    Who can help me?