Sounds similar to this:
https://www.mobileread.com/forums/sho...d.php?t=150609.
I don't recall anyone having this particular problem before now. What's going on??
Good luck!
Edit: I just saw a post from DianNC who said when she(?) put an SD card in half the eink screen went black. Do you have a microSD card installed?? Just a chance, but you might try removing it.