My confusion is because the “out of space” implies the disk is full (and this is why the “df -H” command is suggested…to check if space was out…flash tools require a lot of space if an image is being generated).
Are you asking where the “flash.sh” script is located? If so, then this is from the driver package for that release. JetPack is a graphical front end to this, so if you have run JetPack, then you will have a “Linux_for_Tegra/” subdirectory, and “flash.sh” will be within that. Device tree files (dtb files) will be in either the “kernel/” or “bootloader/” subdirectory to that.
The Jetson must of course be in recovery mode with the micro-B USB cable connected to the host.