Sorry that I cannot answer that. Actually I always suggest any user needs to flash any kind of jetson product with sdkmanager in the first time you get it.
If you only need to update sdcard image on jetson nano and never tried sdkmanager before, then you are lucky enough that you didn’t break the system before.
Since it is embedded system, it is common that someone accidentally breaks their bootloader or something else.
For example, lots of users try to write their own kernel driver too.
It is easy to break system if the kernel driver leads to system crash. For those cases, it is common to reflash the system.
Jetson nano is more like a beginner level product which can run with sdcard image. But any AGX series products (Xavier AGX/ Orin AGX) is unlike nano. It does not run with sdcard image. Thus, needs to flash the board in the first time.
Ubuntu 20 Live will work if the kernel supports loopback. “Probably” it does (I haven’t tried)? The main trick is that you need about 50 GB of disk space formatted as ext4, so you can’t for example run this on an NTFS or VFAT partition.
Incidentally, Jetsons don’t have a BIOS, and all of the equivalent is in software (for the AGX Orin it is in partitions). This is why Jetsons cannot self-flash. The Jetson becomes a custom USB device in recovery mode, and part of the flash software running on the host PC is the “driver package” (named well since it is the driver to that custom USB device). In a way you are updating the equivalent of the BIOS when you flash, and not just bootloader and o/s.
