2. Extract the rom file and identify the modem file namely NON-HLOS.bin (in the unlikely event of having a different filename, figure out what the .bin files contain using google search and copy and use the file that has the modem band information instead of the mentioned file)
3. Copy this file to the folder where the adb toolkit is installed (Default :C:\Program Files (x86)\Minimal ADB and Fastboot)
4. Connect your phone to PC with a data cable & Allow USB debugging
5. Execute the desktop shortcut and type "adb devices" if it returns a number youre good to go.
Input the following
adb reboot bootloader (If you are already on the bootloader skip this)