> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cyberup24.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Boot Failures

A LARK appliance that won't boot is almost always caused by one of three conditions: the management/network module is missing or not fully seated, the power supply connection is incomplete, or the system encountered a POST error during startup. This page covers each cause in detail with diagnosis and resolution steps. Work through them in order — the most common cause is listed first.

<Warning>
  Do not attempt to force-power the appliance on repeatedly without first confirming the management/network module is correctly installed. Doing so will not resolve the underlying issue and may mask fault indicators that would otherwise help you diagnose the problem.
</Warning>

<AccordionGroup>
  <Accordion title="Management/network module not installed or not seated correctly" defaultOpen icon="circuit-board">
    The management/network module is a removable component that provides both the baseboard management controller (BMC) and the primary network interface. The LARK will not complete its boot sequence if this module is absent or improperly seated — this is the most common cause of boot failures in the field.

    **How to diagnose**

    1. Power off the appliance fully by holding the power button until all indicator lights go out.
    2. Locate the management/network module slot on the chassis — refer to your model's quick-start card if needed.
    3. Inspect the module. If it is missing entirely, the boot failure is confirmed. If it is present, check whether it is flush with the chassis and whether the retention latch (if equipped) is fully engaged.
    4. Look for a loose fit, a visible gap at the connector edge, or any physical damage to the module or slot.

    **How to resolve**

    1. If the module is missing, install it now. Align the module with the slot guides and press firmly until it seats completely. Engage the retention latch if present.
    2. If the module was partially seated, remove it fully, inspect the connector pins for damage or debris, and reseat it carefully until it clicks into place.
    3. Power the appliance back on and observe the boot sequence. The system should now progress through POST and begin loading the OS.
    4. If the appliance still does not boot after reseating the module, proceed to the other causes below.

    <Note>
      After reseating, wait at least 10 seconds before powering on. This allows the module's onboard controller to initialize before the main board asserts power.
    </Note>
  </Accordion>

  <Accordion title="Power supply not fully connected" icon="plug">
    An incomplete power connection can cause the appliance to appear completely unresponsive or to shut down immediately after power-on. Unlike a module issue, a power problem will typically show no LED activity at all.

    **How to diagnose**

    1. Check the power cable at both ends — at the rear of the LARK chassis and at the wall outlet or power strip.
    2. Confirm the outlet is live by testing it with another device.
    3. If you are using a power strip or UPS, verify it is powered on and has not tripped an internal breaker.
    4. The LARK requires a stable 110V/120V AC supply. Check that your facility's supply voltage is within that range.

    **How to resolve**

    1. Disconnect and firmly reconnect the power cable at the chassis end. Many IEC connectors have a retention clip — ensure it is engaged.
    2. Reconnect at the wall or power strip and attempt to power on.
    3. If you were using a power strip, try connecting directly to a wall outlet to rule out the strip as the source of the problem.
    4. If the appliance still shows no signs of power (no LEDs, no fan spin), the internal power supply unit may have failed — see [Diagnosing LARK Power Supply Problems](/troubleshooting/power-supply-issues) and consider escalating to support.
  </Accordion>

  <Accordion title="POST failure during startup" icon="triangle-exclamation">
    A power-on self-test (POST) failure occurs when the appliance's firmware detects a hardware fault before the operating system loads. This typically results in the system halting mid-boot, displaying error codes, or emitting a pattern of beeps (if a speaker is connected).

    **How to diagnose**

    1. Connect a monitor to the LARK's video output and power cycle the appliance. Watch for any error messages displayed during the early boot phase before the OS loads.
    2. If you have access to the BMC console, connect to it now and review the event log and any captured console output — POST errors are recorded there even if no monitor is connected.
    3. Note any numeric or alphanumeric error codes displayed. These indicate which hardware component failed its self-test.

    **How to resolve**

    * If the error points to a **memory fault**, the DIMM may have failed. This is a hardware issue that requires support escalation.
    * If the error points to a **drive fault**, refer to [Responding to Hard Drive Failure](/troubleshooting/hard-drive-failure).
    * If the error mentions the **management module**, reseat the module as described in the first section above.
    * If the error is unclear or you cannot clear it, refer to [Diagnosing BIOS and POST Failures](/troubleshooting/bios-post-failures) for further guidance, and see [When to Escalate](/troubleshooting/escalation-criteria) if the issue persists.
  </Accordion>
</AccordionGroup>