Hi 18361273529,
Please try below method:
- Press reset button to reboot your Xavier
- Try to change others HDMI monitor or cable
- Try to flash by manually:
$ cd /home/<username>/nvidia/nvidia_sdk/JetPack-4.2.2_Linux_P2888/Linux_for_Tegra
$ put your device into recovery mode
$ sudo ./flash jetson-xavier mmcblk0p1