[Miscellaneous Android Development] mexamilian:
try this

im not sure but are you running the latest platform tools?

make a file on your root C drive called BV9100

download and install 7zip https://www.7-zip.org/a/7z2002-x64.exe

Download the latest file from here https://dl.google.com/android/repository/platform-tools-latest-windows.zip

downloaded file will be "platform-tools_r30.0.5-windows.zip

right klik the downloaded platform-tools_r30.0.5-windows.zip select 7-Zip then Open Archive

there will be a folder "platform-tools", double klik the file to go further

Select all files there (ull see something like api, lib64, systrace, adb.exe.....etc)

drag all selected files in that folder to C:\BV9100

go to C:\BV9100

you are in BV9100 folder,

up top where address bar is klik it,

press delete key

type cmd and klik enter

cmd will pop up with info:

"Microsoft Windows [Version 10.0.19042.685]

(c) 2020 Microsoft Corporation. All rights reserved.

C:\BV9100>"

Go to setting and write down ur build number.

From ur earlier posts looks like you are on EEA which is EU model POST #13 " BV9100EEA00016800, (EEA means EU version) I have non EEA version download this file for EEA your version:

https://bbs.blackview.hk/viewtopic.php?t=532355 (1st link)

direct link https://mega.nz/#!ttx1FBKQ!f0rYqyQJypc02ahtcenkmLF4GoBlpnpIc9oTsJVFMDw

save it somewhere,

I suggest making an UNTOUCHED FW folder inside the C:\BV9100

make a folder called FW then a new once inside it called UNTOUCHED,

would look something like this C:\BV9100\FW\UNTOUCHED, place it there.

extract the .gz file, youll get one that says .tar at the end, delete the .gz file

go inside the extracted folder, extract the tar file.

youll get a bunch of folders and files in there such as "calibration, boot.img, cache.img, MT6765_Android_scatter.txt ... etc"

go back to the root of UNTOUCHED folder and create a new folder "20190824_EEA"

go back into the extracted folder where the "calibration, boot.img, cache.img" files/folders

select all and right klik copy or cut

paste into the "20190824_EEA" folder. (this will be your clean/untouched FW that u can use to make clones of and mess around with)

go where the extracted folder the tar file was in and delete it (clean up dupes)

now, go into "20190824_EEA" folder and copy the "vbmeta.img"

paste it into C:\BV9100

SIDE NOTE: make sure the build number you wrote down matches the downloaded one, if not you can risk it and flash it in below steps, but i dont know the outcome on a "clean OEM phone" mines already messed up so im messing around and was able to flash it on the updated OTA fw with no issues, this does not mean you wont have them on your clean oem un-packaged phone. makes me wanna buy another one and clone it since i know now not to destroy the nvnand(hidden). would have saved me a full week worth of 10+h a day research and testing. AAAAnyways next step.

on phone go to display and set timeout to 10min or something long for screen to stay on till we done

go to dev options

check and see if OEM unlocking is GREY and enabled

go "revoke usb debugging auth

klik ok

disable

usb debugging

enable usb debuggin

klik ok

connect original usb cord bv9100 came with to phones port

connect other end into pc port

go back to opened cmd from above

*TIP* you can use arrow key UP and DOWN to "scroll" thru ur typed commands, try it after u typed some.

type

adb devices

klik enter, you get something similar to this:

"

Microsoft Windows [Version 10.0.19042.685]

(c) 2020 Microsoft Corporation. All rights reserved.

C:\BV9100>adb devices

* daemon not running; starting now at tcp:3041

* daemon started successfully

List of devices attached

0123456789ABCDEF unauthorized

C:\BV9100>

check your phone box popped up asking to allow check box klik ok

klik arrow key up

adb devices will be selected, klik enter

you get the following:

"

C:\BV9100>adb devices

List of devices attached

0123456789ABCDEF unauthorized

C:\BV9100>adb devices

List of devices attached

0123456789ABCDEF device

C:\BV9100>

"

double check you your firmware version on phone make sure it matches the one on https://bbs.blackview.hk/viewtopic.php?t=532355

now, extract your firmware file you downloaded from

follow post #7 and then #10(<very important for TWRP to work)

Dont forget to set your 10min display back to what evevs 15-30sec timeout

then what you wanna do is use MTK Droid Tool (latest v2.5.3 or god knows 2.5.3b) and make nvnand backup of ur IMEI, S/N and other very important thinks.

Sorry for the long post i hate to read all this myself but i do appreciate thorough posts like these. Once i start i go waay into details, i should just make a video and paste the link.