Grab the X98 Air 3G 4.4.4(C5Jx) mirek190_v4.2 rom and use the bat file within to flash android and reinstall partition tables choosing to have the largest partition for Android. If it doesn’t recognise your tablet when its in the droitboot mode install this updated version of IntelAndroidDrvSetup https://software.intel.com/en-us/blogs/2015/04/30/new-intel-usb-driver-version-190-for-android-devices-available-for-download
This is how I went from a windows only C5Jx to a dual boot again.