Changing firmware in phone will erase all of your data.
All described operations you are doing at your own risk.
If want save your data do backup before start.
10. Now full rom backup from phone will be readed and saved in selected directory.
Always is good have it before any play with phone like firmware change, root, frp reset becouse in full backup you got everything for repair damaged phone(nv zone, imei zone, simlock zone, bootloader, preloader etc.) even if you full erase it.
To write this backup to phone if something go wrong we will write manual in future for now need go to professional service center with it and they will fix phone for you.