We cannot receive any signal from TegraB

It seems that you have not installed or flashed DRIVE OS before. To flash it, you can use SDK Manager which is a tool that runs on your host system. I recommend referring to the DRIVE OS 5.2.6 Installation Guide for NVIDIA Developers (assuming that you’re using DRIVE OS 5.2.6). Make sure to select only the Xavier you want to flash in the step shown below: