Ouch.
I swear that all the modifications I suggested did no harm to my device and should have been safe to apply on yours.
Anyway, you may want to try cold-booting the device (Holding the power button for a veeeeeeeery long time, like 30s). Maybe that helps. Otherwise,
https://www.mobileread.com/forums/sho...d.php?t=161806 might be useful.
Hope you get it working again.