# Troubleshooting

## USB drive does not appear

Check:

- The board is actually receiving USB power.
- Input voltage is within the USB range.
- Your USB cable supports data.
- The selected USB port works.
- USB and storage health fields.
- Serial output.

Reconnect with hazardous outputs disconnected.

## Unknown power source

If the board reports an unknown power source, inspect:

- Battery voltage
- Battery polarity
- Wiring
- Voltage-sense circuit

Supported classifications are:

```text
USB:     4.5 - 5.5 V
1S LiPo: 3.0 - 4.35 V
2S LiPo: 6.0 - 8.4 V
```

Do not continue using an unknown source until the cause is understood.

## Calibration fails

Place the board on a stable surface.

Remove:

- Movement
- Vibration
- External disturbances

Then inspect:

```text
IMU_STREAM_OK
BARO_OK
FAULT_REASON
```

Also check serial output.

## Red blinking LED

A rapidly blinking red LED indicates a latched fault.

When this occurs:

1. Keep hazardous hardware disconnected.
2. Read `FAULT_REASON`.
3. Inspect the health checks.
4. Find the underlying problem.
5. Correct it before rebooting or retesting.

The pyro output is disabled while the critical fault is active.

## Settings do not change

Check:

1. Setting names are spelled correctly.
2. Values use the expected format.
3. The file was actually saved.
4. The USB drive was safely ejected.
5. The board was reconnected or rebooted.

Only edit normal configuration values in:

```ini
[settings]
```

The diagnostic sections are generated by the firmware.

## Flight log is missing

Wait until the landing and save process has completed.

Then reconnect over USB and inspect:

```text
/logs
```

Also check:

- Flash filesystem health
- Serial output
- Fault state

Do not remove power while the board is writing the log.