What image did you use ?
The same happened to me when i tried to flash Raspberry Pi OS on my cm4 but unfortunately both screen and keyboard were not working…
I tried to flash Clockwork OS, it worked, but the uconsole was turning off after few minutes of use.
Finally I flashed Bookworm and it works perfectly.
You can find the bookworm thread here
and the os images in the drive below:
https://drive.google.com/drive/folders/1tw2uPVPsFDhQ5Onx4mlllYexUDmDp0eK?usp=sharing