I believe it is a just released model,
https://shop.boox.com/collections/all/products/page. TBH I'm not sure which loader I ended up using. It just worked using the newest edl without me having to specify. The EDL part worked fine, and adb/fastbootd worked fine. Bootloader fastboot has also worked without any problems on other Android devices. I'm running on OSX. When in bootloader mode I looked at the lsusb equivalent (System Report) and didn't see any unknown devices listed. I will try on a windows box in case it is an osx weirdness