Is it possible to completely reinstall firmware?

Kindle Paperwhite 2nd gen. History: (1) would not get past screen-saver although charged (2) would not perform factory reset (screen saver flickered momentarily) (3) software "repair" found via Google and downloaded to Kindle from PC (4) Now totally unresponsive and white "grid-lines" have appeared towards bottom of screen saver.

Q1: Were/are (1) and (2) repairable?

Q2: can I remove (3) and fix (4) by completely reinstalling the firmware?

Thanks for any practical help you can give.