Hello I wanted to know if I could downgrade my smartphone? Because I read
WARNING: Please remember that after-party flashing this firmware, downgrading to in previous firmware version will brig(brick) to your device.
Gift(Donation) t downgrade to previous firmwares!
I installed(settled) the BV8000Pro_blackview_2018062921 version but it does not suit to me. I can return to a version 7.0?

Original text 
Bonjour je voulais savoir si je pouvais downgrade mon smartphone? Car j'ai lu
WARNING: Please remember that after flashing this firmware, downgrading to à previous firmware version will brick your device.

Don't downgrade to previous firmwares!
J’ai installé la version BV8000Pro_blackview_2018062921 mais elle ne me convient pas.  Je peux retourner à une version 7.0 ?

Yes, you can downgrade without problerms.
Such message was about previous firmwares in the list.

ok smart phone is downgrade 
For downgrade i  use
SP Flash Tool v5.1804
Checksum_Generator_5.1724.00.00

ANDROID 7.0 BV8000Pro_blackview_20180308


If you need I can try to make a tuto young