as V01_20170517 doesn't seem to be an improvement of firmware at all, I suggest Blackview to re-release V01_20170414 as a "new" update (like V01_20170530) so that people can use their phone again

So please stop searching for the reasons why 20170517 doesn't work as expected,
just re-release better version (previous release) so that people can use OTA update!
THANKS!
~dee