Blank white after using many setup

Hi David!

I have claimed for a full refund, that's okay for now. But the interesting thing that is I have been trying to avake the display somehow. I downloaded random libraries and the LCDWIKI KBV library has done something.
Running colligate test resulted a flickering screen, and it seems it has a vertical mirroring effect. The result is attached as a picture.

What do you think, changing the cpp file of the library will result something in better operation?

Thanks for help:
David