Replying to this because here we are a year later and I had the exact same thing happen to me. I had ordred a second X23 to mess around with and ordered it with Volla OS but it came with UT and am having the same errors as you. Two questions:
What is "sideloading" ? Is it a different way of saying dual booting ?
Any chance I can get those zip files off you in some way or form ?