# Installing Firmware in a Bricked Device

If your unit is bricked due to a botched firmware update, the software can still be installed by using the Bricked Mode Recovery option.

{% hint style="info" %}
Bricked units are quite rare. Cerulean Sonar is always happy to recover bricked units for you for no charge. Send the unit to us and we will try to send it back out the same day. We only need the electronics, we do not need the cables and penetrators. Mk II "P" package units will need to be returned in their entirety. 
{% endhint %}

To recover a bricked unit, the key is to get the device into hardware bootloader mode, where the low-level hardware can work with CeruleanTracker to restore the firmware. The hardware bootloaders are primitive and finnicky, so the process must be followed carefully. 

* The device must be physically opened (except for Mk II S package).
* CeruleanTracker should be started.
* A cable must be connected between your PC and the device. In the case of an ROVL Transmitter or Transponder, you may need to manufacture a special cable. DVLs must be connected via a serial port (the Ethernet hardware is not smart enough to install firmware in a bricked unit).
* See [Putting ROVL Devices into Hardware Bootloader Mode](/c/ceruleantracker/installing-firmware/putting-rovl-devices-into-hardware-bootloader-mode.md) or [Putting DVL Devices into Hardware Bootloader Mode](/c/ceruleantracker/installing-firmware/putting-dvl-devices-into-hardware-bootloader-mode.md)to see how to get into hardware bootloader mode.
* Tell CeruleanTracker to which serial port the device is connected.
* Click the Bricked Mode Recovery button. The Firmware Updater window will open.
* The Firmware Updater window will operate very similarly to how it operates for updating firmware. The differences are, you must specify what kind of device you are using, installed firmware revision dates are not available and you cannot opt out of installing files.
* Tell the Firmware Updater window what kind of device you are updating.
* Click the BEGIN button and observe the operation.

{% hint style="info" %}
Once in hardware bootloader mode, be careful not to request or send any data to the device! A single stray character will confuse the hardware bootloader and the operation will fail. 
{% endhint %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.ceruleansonar.com/c/ceruleantracker/installing-firmware/installing-firmware-in-a-bricked-device.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.