Boot up radio in tftp mode by pressing the reset button for ~20seconds or till you get the crossing blinky lights.

Enable TFTP
In Windows, search for
“turn windows features on or off”
Open up and select tftp client. Then hit OK.

That should install the tftp client

Flash firmware
To flash the firmware, open up a command prompt and run the tftp command

tftp -i 192.168.1.20 PUT "\Users\bob\Downloads\XM.v6.1.3.31939.171117.1238.bin"