Please remove sim cards and micro sd's from your phone. Then perform a factory reset (total wipe) from the recover my menu, as showed here:

viewtopic.php?f=192&t=334922

After that, don't load your previous Google backup. Just start from scratch.

Thanks for the quick preply!
Unfortunately, it didn't work. I removed my SIM (I didn't have a micro-SD in the second SIM-slot) and then I turned the power off. Following the tutorial, I started by holding down the volume up button and then the power button. I tried holding the buttons for over a minute, but the Blackview logo doesn't appear.
Instead, a small side menu keeps popping up with the following text:
*****
Select Boot Mode:
[VOLUME_UP to select, VOLUME_DOWN is OK.]
[Recovery Mode]
[Fastboot Mode]
[Normal Mode]
****
Since I couldn't get into recovery mode in the way the tutorial says, I picked recovery mode from this side menu. I then used 'Wipe-data/factory reset' and turned the phone off afterwards.
But after turning it on again, I still get asked for a Privacy Protection password, so it didn't fix my problem...
According to the recovery menu, my phone type is BV9000-F.
I there anything I did wrong or anything else I can try?

Can you please post some screenshots or a video about you performing a total wipe and getting asked about the privacy code? 

This may be useful...
https://visihow.com/Bypass_Privacy_Protection_Password_on_Android

Here are photo's of the total wipe:
SIM tray is empty
the small side menu, choosing recovery mode
recovery mode, choosing total wipe
confirming total wipe
after the wipe, turning the phone off
phone is rebooting
still asking for the privacy password

I tried method 3 from the website you linked to, but it doesn't work. Methods 1 and 2 don't work either, because I get asked for the privacy password even with my original SIM.

Rob_79 wrote:

Here are photo's of the total wipe:
SIM tray is empty
the small side menu, choosing recovery mode
recovery mode, choosing total wipe
confirming total wipe
after the wipe, turning the phone off
phone is rebooting
still asking for the privacy password

I tried method 3 from the website you linked to, but it doesn't work. Methods 1 and 2 don't work either, because I get asked for the privacy password even with my original SIM.

Keep trying the other methods showed in the link i posted

I tried method #6 and that worked! Apparently the 'anti-theft PIN' is the same as the 'privacy protection password' I needed.
(Now I wish I hadn't factory reset my phone)

Thanks a lot for your help!

Rob_79 wrote:

I tried method #6 and that worked! Apparently the 'anti-theft PIN' is the same as the 'privacy protection password' I needed.
(Now I wish I hadn't factory reset my phone)

Thanks a lot for your help!

You are welcome!