It's firmware version is currently "BV5000_C1_Blackview_V0.7_20160304", as can attest this screenshot :

I know there is more recent versions of it.
I have an error when trying the automated update, that says in my native language that my device is damaged, so the function is desactivated :

I downloaded some firmwares from around this very forum, trying to install the updates from my SD card. But I was confronted to some issues :
- It seems there is an order to do the updates, but I have no idea what it is.
- I struggle to enter in recovery, as my firmware is pretty old. Most of the directions I found online don't apply, and I end up reaching it by random tests. I would like precise directions, it available.
- I know how to use the Bootloder, and have ADB/Fastboot commands installed on my computer, but it seems any firmware update can be applied that way.
- The factory reset only ease personal data. My issue with the automated install remained after several factory resets, so I assume it will not help my issue.
Details I think, worth be mentioned :
- I'm a Mac User. I have no Windows computer at reach.
- Mega to download firmwares is tedious. I used it because there were no other option.
- I rooted device with Kingroot. Unrooted it to make updates afterwards. Is actually completely unrooted.
- I'm planning on installing the Xposed Framework once the updates are eventually done. Any direction on installing custom .zip softwares with the built in recovery is really welcome. Else, I would appreciate a firmware with any custom recovery installed.
I can give additional information if needed.
Thanks in advance !