How can i install the firmware i want to my Hazel j20i

Hi everybody.I have a Hazel j20i with this firmware R7CA064 ADRIATIC.
But i have problems with the signal.I have read that the only firmware
that can fix signal problems is R7CA065 but i cant find it and also i dont
know how to install it if i will find it.Please help me.

it's very simple
use omnius, and download flash files from omnius
registration and flashing a2 is free.
your phone is a2

omnios rocksss