Sorry for your loss
Your display was damaged even before you opened it. Seems like some of your pixels burst...
Unless you killed your bootloader/kernel/recovery partition, it's not necessary to open the device to do a factory reset: [
deleted vidme link]
So opening should only be necessary to replace bad battery / when the SD card died altogether.
And yes, you have to be verrryyyy careful when opening it. I almost died opening mine:
https://www.mobileread.com/forums/sh...66#post2998466
https://www.mobileread.com/forums/sh...84#post2998984