Hi Vasilis,
I’m sorry I couldn’t help concerning your specific request, as I don’t have, for now, enough skills in the mechanisms of dual-boot Win-Android devices. I wish I could have provided some help, sorry mate. I just know how to rewrite the Android part of this tablet with Mirek190’s custom Android ROM, as long as the partition tables of your device are NOT damaged, using the Intel Device Management sofware provided in this forum.
I hope you can find a way to fix your device 🙂
Cheers.