If using Linux, you can use dd. Oh and the sysNAND version doesn’t matter, it won’t boot if it’s to low, but if your EmuNAND is updated, it’ll boot right up.
sudo dd if=boot0.bin of=/dev/sdj bs=1024K count=4 seek=1024 oflag=seek_bytes status=progress
sudo dd if=boot1.bin of=/dev/sdj bs=1024K count=4 seek=4195328 oflag=seek_bytes status=progress
sudo dd if=full.00.bin of=/dev/sdj bs=1024K count=4294836 seek=8389632 oflag=seek_bytes status=progress
sudo dd if=full.01.bin of=/dev/sdj bs=1024K count=4294836 seek=4303225856 oflag=seek_bytes status=progress
sudo dd if=full.02.bin of=/dev/sdj bs=1024K count=4294836 seek=8598062080 oflag=seek_bytes status=progress
sudo dd if=full.03.bin of=/dev/sdj bs=1024K count=3213230 seek=12892898304 oflag=seek_bytes status=progress
Those are the commands I used. The boot0 and boot1 is probably the same for everybody, you might not need the bs and count.
To get the seek value you add the previous file size in bytes to the previous seek, so for full.00.bin the previous was 4195328, and the file size of boot1.bin is 4194304, 4195328 + 4194304 = 8389632.
You could make a Python script to do it easily.
Copying all the data to the TXNAND partition. That’s the non hidden partition.
To get the first seek, for boot0.bin, I used a hex editor, wxHexEditor can open drives. Somebody on GBAtemp said offset 3, which is 1024 in bytes.
You also might want to backup the first 30 GB on the micro SD card, so if you screw up, you don’t have to recreate it.
sudo dd if=/dev/sdj of=EmuNAND.bin bs=1024M count=30 status=progress
Oh and /dev/sdj will probably be different, you can get it by “sudo fdisk -l”.
It’s funny, the one time I backup part of the micro SD card, it works.
Somebody else has instructions on GBAtemp, they put all the files in one big file.
How can you tell when anything ends in a hex editor? Oh wait, wxHexEditor might. I like one file at a time better, because you have to use seek.
Might not work if you have more full files then me, you might need their method. Or maybe macOS has dd limitations.