I have a problem at my 4 month old smartphone BV6800pro with filetransfer and backup to a windows10 computer.
In the beginning, when I connected the Blackview factory-cable to the usb port, there was a message at the smartphone top-sceen to select charging-options.
When i selected 'Transfer files' the connection to the computer was ready and i could backup the files from the smartphone.

But since some time, the screen-message for charging-options doesn´t display at the top of the smartphone. Therefore I can´t change to
'Transfer files' and can´t get access to the smartphone by the windows-explorer.

I tried another usb-cable with the blackview-adapter, same problem.
Restarting the smartphone and computer is no solution.
Charging the battery is possible with both cables.

Android Build-Number: BV6800Pro_S592V1.1_2090320V23

Any ideas how I can get access again to backup files from the blackview by usb connection?

Best regards from germany.
Cari...

I can't understand what happened to your phone from here. Said that, the most rational thing to do is to perform a total factory reset and try again. You can backup all your stuff via the Google Backup feature.

Here you can find how to perform a factory reset from the recovery menu:
viewtopic.php?f=192&t=334922

Be also sure to insert the usb cable in a correct way.