Hi,

Quite a strange situation..... Battery was 30% so I decided to charge the phone.

After few minutes, red led as charge indicator disapeared and srceen sarts flashing : blackscreen/Blackview logo.

On/off button does not work.

Any idea ?
Thanks

If you like and you could try to flash a new rom to fix it.
Here is a tutorial: viewtopic.php?f=176&t=141026#p322236

If you flash it be sure to follow the guide to not damage your phone.