R-Car/Boards/Yocto-Gen3-CommonFAQ/fastboot.sh script stacks with "waiting for any device"

fastboot.sh script stacks with " "
Host PC could not detect the board after rebooting to fastboot or fastbootd mode. Please make sure that device is connected and displayed in the output of “fastboot devices” command.

If you get next error: no permissions (user in plugdev group; are your udev rules wrong?) You can fix it with variants:
 * 1) Install fastboot to your system. (doesn’t help in some cases)
 * 2) Manual variant (sudo need)
 * 3) * Create file 51-android.rules in /etc/udev/rules.d/
 * 4) * Write to this file next line: