I opened up the kindle yesterday, thanks to clear instruction found here:
https://www.youtube.com/watch?v=6BhTqbslijc
and suddenly the device worked properly again. Bizzare... But I heard some rattle while opening the back panel. In any case, if someone encountered this trouble, maybe we can open the panel and remove the battery, basically completely turn off the unit, then turn it on again and see if the problem disappears.
Wirawan