It appears that a new bios came out for the K6C3 model yesterday. I found this post on the Teclast forums which covers upgrading the bios from 1.00 to 1.05. After that you should be able to flash Android. Sadly, I didn’t bring my tablet with me today so I can’t try. Also not home tonight so my earliest try will be tomorrow.
What I can make up from the Teclast forums is that the RAM and Camera have changed between the two models. I really hope there will be a way to flash Android for the K6C3 model. Would just hate to get stuck with just Windows 10