Hello,
my jetson nano 4Gb was running smoothly but now it got stuck when boot, (as shown in attachment)
the sd card has OS: ubuntu 20.04, L4T: 32.6.1, Jetback: 4.6
Have you tried to re-flash it with SDK Manager?
I need to install ubuntu 20.04, so I didn’t try SDK manager
How did you install Ubuntu 20.04 on your Jetson Nano?
The newest Ubuntu version we officially support on Jetson Nano is 18.04.
that is right, I didn’t use the official version.
I have used unofficial version created by another developer
Then that’s not what we should support.
Incidentally, the boot chain for a Nano is quite custom. So is the GPU driver. Releases are not even remotely as interchangeable on a Jetson as they are on a PC. It is difficult to get Ubuntu 20 to work on a Nano, and even if it works, it may not be entirely functional (especially the GPU).