Hi @Aleblanc,
Have you made any significant changes recently on the box? For e.g. upgraded Ubuntu or Jetpack or something similar?
If I understand correctly the LED is on but the HDMI display is not working. Is the box available on the local network if you ping it or connect via ssh?
Is the box available if you plug a USB cable in the OTG port and connect to a host machine? For this you can follow the instructions in the “Force recovery mode” section: Reset your ZED Box Orin NX - Stereolabs