This is a fix for mkb jingpad devices.
If you can successfully flash official .pac file to your jingpad but its screen is always black...
Check the serial number of your device, if there is a "mkb" inside, then your jingpad might be a device for engineering (while "mkc" device is for users), which means jingling team send an wrong device to you.
If this happens you can compile the android source code with this fix provided by Chinese user @追梦人.