How to production of nano module image files,the nano module is B01 version with emmc

Dear Sir,
I am having trouble making a mirror of the B01 nano module. I now have the Linux_for_Tegra 4.2.3 downloaded via sdkmanager.
I make sure that the nano board to be mirrored has entered recovery mode and connected to the pc via usb.
Execute the command: sudo ./ -r -k APP -G /home/somebody/system.img jetson-nano-emmc mmcblk0p1
It gives the following error: 00000004: Failed to get an accessor of secondary boot device

hello 932365660,

it’s an known issue that performing image back-up failed.
please check discussion thread for same failure, Topic 1064479.

you might have an alternative way, could you please use dd commands to back-up APP partition.
for example,

$ ls -al /dev/disk/by-partlabel
lrwxrwxrwx 1 root root  15 Nov  5 07:03 APP -> ../../mmcblk0p1
$ sudo dd if=/dev/mmcblk0p1 of=/tmp/Backup.img bs=131072

once you had clone the APP partition (i.e. back-up.img), and then replace $OUT/Linux_for_Tegra/bootloader/system.img with it.
you should also adding “-r” commands, which skip building and reuse existing system.img to flash boards.