Hi,
I did not find how to answer the pm, I post my answer here.

Sent: 10 hours ago
From: blackview_admin
Recipient: R404a 
Another problem, in addition to the ejection of the SD card alone, I also noticed that the phone turns off too alone.

the problem accumulates and I never see my published topic, why?
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Hi, 
It's available for you to make a list about all problem on your BV9700 pro?
Our tech team are willing to help.

1: the phone goes off without request when I want to unlock with the fingerprint.
2: the sd card is ejected without any request (forced to restart the phone so that it reappears and disappears some time later) sandisk class 10a 64Gb (never had a problem with my old phone), result impossible to transfer my files or to save photos / videos when I take a picture or video or listen to music ...
3: Can not connect my phone to my windows 10 computer with the windows 10 phone app in bluetooth, yet they see each other.

here at the moment, hoping not to find other problem with this phone that I appreciate anyway.
Regards
Steph

1. Enter *#87# to test the fingerprint sensor;
2. Does the SD card work well on another device?
3. I can offer you a video about how to connect the phone to the computer, pls send me an email and I can reply you with our test video.
(I have sent you my private email account via PM, pls check it)

Please send me the video to on my pm. Thanks

*#87# is invalid code 

Hello,
I did the tests, all that I could test is ok, but the sd card is still ejecting can time after reboot, I'm waiting for a new sd card to see if this problem continues or not, I would post my answer once I would have received and tested.
Regards
Steph