I havent had time to fix the tablet. Now I got time and I am back in this thread.
I did use ManufacturingFlashTool as you said before, but no avail. It just stops at 26% telling me it could not find partition table it requires.
I checked the partitions/drives also with diskpart in your provided Windows install (what should have all drivers for loading eMMC chipset up)
As I tought, it couldnt see eMMC internal drive, tho it can clearly see my USB Drive.
And as I told in my first post the Chuwi seems to have problem detecting eMMC chip. It's either bricked chip or it could not detect it because some software glitch.
Checking around this forum, it seems many people have the exact same problem.
I am waiting for a fix for it, cause it seems I am unable to find it myself.
And NO. Telling us to "Reinstall system" when we can't do - is not the answer.