A black HDMI screen does not tell you whether your Sige7 failed to boot or whether Linux started without usable display output. Start by collecting evidence from both the boot process and the display connection.
1. Record the image and display setup
Write down the exact image filename, download source, kernel version if accessible, monitor model, and cable or adapter used. Check whether you installed a desktop or server image: a server image does not imply that a graphical desktop should appear.
With the board powered off, connect the monitor directly using HDMI where possible. Select the correct monitor input. For an initial check, remove HDMI switches, capture devices and conversion adapters from the signal path, and try a known-working cable and monitor.
ArmSoM’s display documentation covers HDMI and other display interfaces. Follow the instructions for your exact board and image.
2. Check whether the board reaches Linux
Open a debug UART terminal before powering on the board and save the full startup log. Follow our UART boot-log guide.
- If startup stops before the kernel, provide the early boot log first.
- If a serial login prompt appears, Linux has reached a login service; investigate the display path next.
- If SSH works, report that too. A working network login is useful evidence even when HDMI stays blank.
3. Collect display information
If you can log in through serial or SSH, run:
uname -r
ls /sys/class/drm/
For each connector directory shown, look for a status file. For example, only if this path exists:
cat /sys/class/drm/card0-HDMI-A-1/status
Connector names depend on the kernel and driver. A connected result reports connector detection; it does not prove that a desktop is running or that the selected video mode is usable. Missing connector entries are also worth reporting.
4. Share a reproducible report
Include the image filename, monitor and cable details, full boot log, connector status, and whether serial or SSH login works. State whether the screen is blank from power-on or loses its image at a specific stage.
Change one item at a time and record the result. This makes it easier to tell whether the issue follows the image, cable, display, or board.