This is a DFI-ITOX product, please contact them directly for support.
the i.MX53 is capable of booting from an SD card with the correct HW configuration. One solution would be to load the Ubuntu image to the SD, and make the proper HW configuration. to have it boot from there.
MFGTool, is looking for our SABRE tablet, based on i.MX53, that is why you are getting that error. It alswo requires a specific HW configuration to have it in load mode.