can't get it working on WinXP-32bit (VCOM driver INF-file for XP dated 05/30/2011, version 1.1123.0) and neither on WIn7-64bit.
Used SP-flashtool for MT65xx Preloader - version 2017/04/27 12:31
Get error S_BROM_DOWNLOAD_DA_FAIL (2004) indicating communication problem due to cable or hardware.
- Replaced USB-cable by another Blackview backup cable.
- Battery fully loaded at 100%
- Bootloader NOT unlocked
- USB-debugging on
- USBDEVIEW checked if any other driver makes problem.
See picture in low-resolution; note that
standard USB-masstorage function allow reading / writing from PC to BV7000 thus USB-cables should be oke, inclusive port-connectors!!!!!!

Question: is the flashtool MT65xx also suitable for the CPU MT6737T of the BV7000-standard?
EDIT: Blackview BV7000 after next try on other USB-port initially same error as above but next try on
this USB-port BV7000 totally bricked.
Red-LED keeps on burning while no loading is ongoing. Long pressing power button and nothing happens anymore. What to do???
No answer from Blackview_admin, so i decided to open the case and disconnect the battery to reset the somehow-looping-flash-program in the BV7000. That did the trick but note: opening the case with T5-torx and small PH00-screwdriver is not everybodies job! I made the error to put one small T5-screw at the position where a long t5-screw should be and broke the tread in the case partly. Thus pay attention to put TWO a bit larger T5-screws at the correct position beside the camera lens. See image and the two red arrows!!
Thus i'm still looking for the correct version of drivers + flashtool to do the job without bricking my BV7000!!