: This is an official or semi-official stock firmware image. When used with the correct flashing tool (like SPD Upgrade Tool ), it is highly effective at resolving "boot loops" or system hangs [2].
: The main instruction file that tells the flashing tool where to put the data. System Images : boot.img , system.img , and vendor.img . 151O001021.7z
: USB drivers necessary for your PC to communicate with the device in "Download Mode." Professional Verdict : This is an official or semi-official stock firmware image