Touch Touch sensor responds incorrect

Hi! I have bought my Kobo Touch N905 not new (seller told it was unused, but it's not true). I checked it on post, opened a menu, a book - all worked. Later I noticed, that Kobo worked slow and made factory reset. After that I suffer.
Touch sensor works randomly. I need to tap a lot of times to open menu or book. Pages turn in random directions. I opened "sketch pad" (it was hard) and tried to draw lines and dots - results are on photos.
I tried to load all versions of firmware one by one, but this bug stays.
Once the problem has gone. I even have drawn a circle and straight lines in "sketch pad". Then it came back.
I have found many similar cases on the internet and no one solution, that works for me. If you have any thoughts about it, please, help!
P.S. Sorry for my English :)

P.P.S I made a thread in wrong forum. Can moderator place it to common forum, please?

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