This link was the most helpful overview: https://www.linux-magazine.com/Online/Features/Basic-Hacks-for-Kobo-E-Readers
#cd /path/to/the/ereader/.kobo
cd /media/danaukes/KOBOeReader/.kobo
sqlite3 KoboReader.sqlite
in the sqlite3 prompt, type
INSERT INTO user(UserID,UserKey) VALUES('1','');
then type ctrl+d
to exit
unplug the e-reader