Your Cache is corrupted.
This is what I did on a Samsung and I believe it's the same for most phones.
When the phone is turned off, hold down the 'Volume Up Button' and the 'Power Button' together.
Nothing will happen at first, wait 5 or 10 seconds.
A screen will appear with a small list of options. One gives you the option to factory reset the phone, and another option is to 'Delete the Cache'. So, navigate to 'Delete Cache' and click on the power button once. This will run that option and delete the Cache.
Once the cache is deleted, hold down the power button to turn the phone off. Then turn it back on again and it should boot.
I admit, I'm not completely sure this will work on a Blackview phone, but it has worked on a couple of other Android phones, one was a Samsung S4, can't remember the other. It's worth a go.
How you got to this stage could have to do with how the operating system was installed.
If you can go through these options and it still doesn't work, you will need to re-flash the operating system onto the phone. At least you will be able to do this because the phone at least powers up to some extend.
If you do flash the phone, make sure you flash just the pre-loader first. I failed to do this and now I have a hard-bricked phone which I can't turn on. I'm in the process of fixing that.