backup my Nano

Hi I follow this guide to make a backup of a Arduino Nano that is connected to a machine. https://www.youtube.com/watch?v=Jw-ZSkzd-uY

But when I try with this code

avrdude -C ..\etc\avrdude.conf -p m328p -c wiring -P COM6 -b 115200 -U flash:r:flash_backup_file.hex:i

I get timeout error. I know I have right COM6 port (it say USB-SERIAL CH340 (COM6)) and I have try with different biterate but still same error.

Not sure what more I can do.

That video is for the Mega. The protocol is different on the Nano. So you need to change it from "wiring" to "arduino". The command:

avrdude -C ..\etc\avrdude.conf -p m328p -c arduino -P COM6 -b 115200 -U flash:r:flash_backup_file.hex:i