New rock pi 4 display not turning on

I just got my Rock Pi 4. Really excited, installed my NVMe with debian that I installed using a normal computer.

I plugged in the HDMI cable, and USB C cable, only green light is turned on, and the display is not turned on.

Please let me know what is going on? I am a SBC noob.

Welcome. First at all, make sure it can boot from uSD(microsd) and eMMC before attempting NVMe booting.Do you have a Rockpi4 A,B or C?

Yes, I just tried it and it works!
So Rock PI only works with the ubuntu that is downloaded from rock pi website? Is it safe? can I make my own image?

Sure, you can do whatever you want or you’re capable of.
Here’s a documentation how to do it in armbian:

NicoD also has several instructive youtube videos for armbian newcomers:

In case you want to try it all at once, I recommend twisteros armbian for RockPi4:

Thank you for your answer. So I need to build the image through armbian? I can’t just use the arm image that I download from debian website?

Either option is valid. You can build one image tailored to your requirements or just download a ready made compatible image for your RockPi4.