Yesterday I installed android 7, using this link, given by blackview_admin:
viewtopic.php?f=142&t=119303&start=40#p301212
The whole system worked more or less ok, although there was some issue concerning the three lower screen buttons touch sensitivity - it was way too low. I installed some apps, checked if everything works and then I left the phone charging through the night. Today I switch the phone on and the screen is very dark, especially at the edges, and there is some after-image when scrolling or changing screen orientation - I marked it with red circle in the picture. I reset factory settings - nothing changed. What the hell is that?? What am I supposed to do with that? The screen is hardly usable now!
Some pictures: