A603 Jetson Orin NX 16 Gb flashing does not finsh: Waiting for target to boot-up

Hello,

I’m trying to flash the Jetpack 5.1.1 into the NVMe SSD installed in the Carrier Board A603 for a Jetson Orin NX 16 Gb as per this instruction web page.

In the final step 3, the actual flashing process, it waits for the Jetson to boot-up, which never happens:

***************************************
*                                     *
*  Step 3: Start the flashing process *
*                                     *
***************************************
Waiting for target to boot-up...
Waiting for target to boot-up...
Waiting for target to boot-up...
Waiting for target to boot-up...
Waiting for target to boot-up...
Waiting for target to boot-up...
Waiting for target to boot-up...
Waiting for target to boot-up...
Waiting for target to boot-up...
...
...
Timeout
Cleaning up...

I have tried to connect the uart debug port to the host computer through a usb converter, as suggested here, but with the same result.

How can I solve it?

Thank you