@khubeo I am not sure if this is a software-bug witch came with the update (in this case it should be solved by flashing an older ROM like 20160822 https://mega.nz/#!nl0TmCJK!rB7UDnoTBH8F ... QGS96s8u5A ) or a hardware bug (which you could maybe complain over your sellers guaranty)

I agree with you, this does not seem to be just software bug. I tried downgrading to android 6, then installed android 7 again, but there is no change. But the problem happened just ater first installing android 7, and that is why I keep asking what could possibly cause it, what I can do about it and what is manufacturer's response to this situation.

@khubeo there may be a short circuit or loose cable. You could watch inside the device or talk to your seller for guaranty.
There are also replacement screens (just screens or complete front part) on aliexpress

This is not a cable, I checked and reconnected all cables. This possibly could be a shortcut or blown fuse, but confirming or repairing this is beyond my abilities. Seller is behaving in a similar manner as admin here - avoiding straight answers or ignoring my messages.

I know I can buy a replacement screen, but I think I'd rather get another phone. So far BV has been too much disappointment, problems and wasted time for me to continue using it.

It looks like there was wrong polarization voltage of LCD or something similar. The screen driver is - as I think - in the front panel together with the screen. Replacing if might help. I ordered one. Admin advised contact with bv's service but people wait over six month for as simple part as the speaker.

Admin must have no technical background. The only competence of this person's are some knowledge of English and how to use Ctrl+C & Ctrl+V.

It's fine that BV shows the phone may be used to hammer nails. The problem is they don't mention that this is the main (and soon after the purchase the only one) purpose of BV6000.

Admin does not need to be a technician - but he should contact technicians and try to find some solution and publish it here.

Partially agree, however knowing i.e. what to ask the user before passing a question to the technician would be handy. Technicians are busy inventing phone durability tests for YT (burning BV7000 was so funny) so they need a buffer Often the admin asks questions not relevant to the problem (like location for resetting phone). But maybe it's hard to find one.