I already have a Jetpack installed on the Jetson nano.
The OS is working, but I would like to go back to the original state.
Can I reinstall the system to the same SD card?
I can use these instructions with the same SD card again: Getting Started With Jetson Nano Developer Kit | NVIDIA Developer
Did you mean, you want to format you current SD card and re-flash it?
If so, you can do it. I have done it many times. But, you need to reconfigure and install everything as what you have done during your first boot-up and also don’t forget to have a backup for your files in the SD card.
But based on my experience, when I connect the SD card to my PC, a lot of partition appear to be existed in the previously flashed SD card. So, when you want to format the SD card using the ’ SD Card Formatter ’ as what have been recommended by NVIDIA it might be troublesome. Therefore, I will format the SD card via Windows CMD first with a few commands. Later, I follow the steps as recommended by NVIDIA for the first boot up as in the link you have attached.
Hopefully this is helpful. Good luck.
Everything worked out.