Jetson Nano right password fail to login the Ubuntu fail to login

We got the NVIDIA Jetson Nano Developer Kit, we got all the needed parts you recommended on your website, we followed the instruction carefully and installed Linux and Python and starting using the kit, however, a few days after that we received some kind of unexpected problem, the kit asks for the password and when we enter it, it doesn’t work and we tried several times. we thought it’s something we did that caused that, we had to reinstall Linux and Python and started using the kit again however a few days after that the same thing happened again (enter password and doesn’t take any password).

would you please help us solve the problem ?

Is the device exposed to the internet? Is the login name/pass unique, or is it a default? If you have a default name/pass and the device is exposed to incoming internet connections, the probably it was malicious. University dormitories are a big example of the computers inside being able to talk to each other…or hack.

Thank you for the updates.
Maybe it was hacked. :-(
We have to reflash it

Don’t forget to change passwords immediately after flash.