They have listed their support email as
sales@onyxboox.com . Tried to find some other way of communication, but it seems neither their tiwitter account is not working (taken over by spambots) and postings on their facebook site warns users buying from this distributer.
From other postings it seems my screen is defect and needs replacement. Guess I just have to hope they will respond to my email.
EDIT:
https://www.mobileread.com/forums/sho...d.php?t=167494 , optimism waning.