I have changed the root password on my raspberry pi 4 and it the os will not load.

I am new to kali linux but have experience with other linux distros and the raspberry pi.
I hav imaged kali linux on a 128GB x10 sd card with a kali-linux-2023.2-raspberry-pi-armhf image.
I have downloaded the image from the official website and validated the SHA256 checksum.
The RPI4 is connected with USB-C (has adequate power supply), an HDMI cable, wired mouse and a wired keyboard.

The OS uploaded successfully and was working okay (exploring the OS through the desktop GUI and through the terminal with no changed or additions).

I have changed the root password with:

After receiveing a confirmation that the password was changed successfully, I have performed a reboot using:
sudo reboot now
After the OS was closed for the reboot and before seeng the boot lines, the screen went black and will not do anything even after a long timr (I have waited at least 30 minutes).
unplugging and plugging the USBC produces the same result.

I have imaged the boot sd again and the os uploaded successfully. changing root password again gave me a black screen after reboot oand after unplugging and re- plugging the power.

What can be the issue and what can I do about is?

May thanks!