Possible to recover a bricked Boox Note Plus?

Boox Note Plus was stuck at android 6 which makes a big hurdle to my current workflow. So I've kept it in the drawer for a while.
Yesterday I noticed Onyx had released an upgrade from Android 6 to 9 for Note Pro. Thinking that the only difference is the disk and ram sizes, I boldly tried the flashing and with no surprise it bricked... I cannot enter recovery mode either. I can only do the "Loader" or "MaskRom" flashing.

So, any suggestions that I could follow to unbrick this device? Many thanks.