hi all, probably many people was talking about that issue but i'm an older person

and have a problem to find all answers. my problem is well known to you all - I have white screen in my kobo aura h2o - how this happened ? the reader doesn't work on all books (to be honest worked on one only and gets frozen on the others - just for last few days, before was no problem) so i decided to do a factory reset. after i did it, i went to kobo desktop to finish syncing. after disconnecting from the computer the screen worked for a while and then became white. I've contacted kobo help desk and no help. Find here different ways to try reset it again but no matter what i will do it's back to white screen (white-black-white-black-white during reset). I've seen somewhere an info that the reader can work from external card but i have no idea what to do. if someone can help me with that i will really appreciate it.