I get a similar ghost touch problem on my JB PW4.
Running firmware version 5.11.2
SN G000PPxxx
My device is not registered with Amazon services. Only use KOreader for epub books.
Even without touching the screen the device registers touch input on the bottom part of the screen.
Can be related with this post
https://www.mobileread.com/forums/sh...d.php?t=313862
Any help with this issue ?