# Lock the Bootloader

### Step-by-Step Instructions

1. Click the **Lock bootloader** button in the installer.
2. A confirmation prompt will appear on your phone screen.
3. Use the **Volume Down** button to select:

   **Lock the bootloader**
4. Press the **Power** button to confirm.

<figure><img src="/files/llWspHCRYKgVJKkfqD3P" alt="" width="563"><figcaption></figcaption></figure>

### What Happens Next

* The device will erase data again (this is required).
* The phone will reboot.
* The device state will change to **locked**.

After reboot, your Fastboot screen should indicate that the device state is:

<mark style="color:$success;">**locked**</mark>

### Confirmation

Before proceeding, confirm:

* That you understand all data will be erased.
* That the device state on your phone screen shows **locked**.

- [x] Once confirmed, click <mark style="color:$primary;">**Next**</mark> to complete the installation process.

### Installation Complete

Your device is now running **Castrum OS** and is ready for configuration.

The operating system has been successfully installed and the bootloader is locked.

{% hint style="info" %}

## **Locking the bootloader ensures:**

* Verified Boot is re-enabled
* The system integrity is enforced
* The device returns to a secure state
  {% endhint %}


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