If there's no LED or HDMI output, it might be:
Image Compatibility: Ensure the LibreELEC image supports NanoPi M4.
SD Card Issue: Try reflashing using balenaEtcher or Rufus.
Power Supply: Confirm it's providing stable power.
Hardware Check: Connect via UART for debug messages.
Hope this helps.

Hi, I'm trying to install LibreElec on FriendlyARM NanoPi M4 RK3399 but I'm not seeing anything boot. When powering the device nothing happens - no LEDs, no HDMI output. I am certain that the device is functional - it was running Armbian just before and I've also successfully installed DietPi. Help...