@chtiot
Every mobile have problems, your problem can be related to firmware, or something else, maybe the charger, or the cable, or a fault battery, I could not know.
Flashing the phone is quite easy even for a newbie, don't worry!
When I bought my blackview I followed this tutorial to flash it:
https://docs.google.com/presentation/d/ ... 37e4_0_579Go to the section restore a stock rom, don't follow the root and twrp parts, which are for rooting and flash a custom recovery.
It's quite straightforward: install the drivers, install the flash program, download the rom from this forum (see the rom section, DO NOT DOWNLOAD THE ROM FROM THE TUTORIAL, AS IT IS OLD) and you are ready to go.
If you follow this tutorial I recommend to set the sp flash tool program to set "Download only" instead of "firmware upgrade" as stated in the tutorial.
Firmware upgrade will try to preserve apps, but in your case it is better to have a "clean phone" after the flash.
This is the official link for the 19 december rom:
https://mega.nz/#!wGpWmCbD!eUFH3aAvb8yD ... QHbinVsJmUThis forum also has tutorials for flashing roms.