I spend some time to get this Device working good, and as i see that there are many questions, i may share my experience here.
To tell which Version you have, go to Settings / Phone Informations and find Build-Nr. It should already be B2_... of May 2016, which is the last rom that has been shipped by Blackview for BV2000s B2.
You may readhttp://obel1x.de/doku.php?id=content:an ... gapps_twrp
to understand how you can flash your phone to your choice.