---
title: Reflash Unitree G1 PC2
description: Replace the Unitree G1 PC2 image and firmware with Unitree's JetPack 6.2 release
---

<img
  src={`${(process.env.NEXT_PUBLIC_BASE_PATH || '').replace(/\/$/, '')}/media/unitree-g1-card.jpg`}
  alt="Unitree G1 humanoid robot"
  className="not-prose aspect-video w-full bg-fd-muted object-cover object-center"
/>

## Overview

This guide replaces the operating system and module firmware on the Unitree G1
development computer, known as PC2, with Unitree's JetPack 6.2 image.

You do not need to reflash PC2 to [install Wendy Agent](../../installation/wendy-agent-unitree-g1/).

<Callout type="warning">
  This process erases the target NVMe drive and replaces the PC2 firmware.
  Preserve the original NVMe and verify every device path before writing an
  image.
</Callout>

## What You Need

- The original PC2 NVMe, removed and preserved as a backup
- A replacement NVMe with at least 1 TB of storage
- A native Ubuntu x86-64 computer
- An NVMe-to-USB enclosure
- A USB data cable
- Unitree system image: `g1-nx-j6.2.img.bz2`
- Unitree PC2 firmware: `Jetpack_6.2_nx.tar.bz2`

Download both files from the package folder linked by NVIDIA's
[G1 JetPack 6 flashing guide](https://nvlabs.github.io/GR00T-WholeBodyControl/references/jetpack6.html).
Confirm the filenames and integrity against NVIDIA's current instructions
before continuing.

The two files update different parts of PC2:

```text
Orin NX module
├── QSPI and boot firmware    Jetpack_6.2_nx.tar.bz2 over recovery USB
└── NVMe operating system    g1-nx-j6.2.img.bz2 written to the replacement NVMe
```

Use Unitree's G1-specific image. A generic NVIDIA Orin NX image does not
include the G1 carrier-board configuration.

## Reflash PC2

<Steps>
  <Step>
    ### Preserve the Original NVMe

    Remove the original NVMe from PC2 and keep it unchanged. Write the new
    image only to the replacement drive.

    The original drive preserves its data, but restoring an older JetPack
    release also requires restoring the matching PC2 module firmware.
  </Step>

  <Step>
    ### Write the PC2 Image

    Attach the replacement NVMe to the Ubuntu computer with the USB enclosure.
    List the connected drives and identify the Ubuntu system drive:

    ```bash
    lsblk -d -o NAME,PATH,SIZE,MODEL,SERIAL,TRAN
    findmnt -no SOURCE /
    ```

    Replace `/dev/sdX` below with the whole-disk path for the replacement NVMe:

    ```bash
    lsblk -o NAME,PATH,SIZE,MODEL,SERIAL,TRAN,FSTYPE,LABEL,MOUNTPOINTS /dev/sdX
    ```

    <Callout type="warning">
      Stop unless `/dev/sdX` identifies the replacement NVMe and is different
      from the Ubuntu system drive. Writing to the wrong path destroys that
      drive.
    </Callout>

    Unmount the replacement drive, then write the Unitree image:

    ```bash
    sudo umount /dev/sdX*
    bzip2 -dc g1-nx-j6.2.img.bz2 | \
      sudo dd of=/dev/sdX bs=4M status=progress conv=fsync
    sudo sync
    sudo udisksctl power-off -b /dev/sdX
    ```

    Disconnect the replacement NVMe from the enclosure and set it aside. Install
    it after the PC2 firmware flash is complete.
  </Step>

  <Step>
    ### Enter Recovery Mode

    PC2 has two buttons inside the rear electronics compartment. PWR is the
    upper button. REC is the lower button above the PC2 USB-C flashing port.

    1. Power on the G1 and wait for all three power indicators to remain lit.
    2. Connect the Ubuntu computer to the PC2 USB-C flashing port.
    3. Hold PWR and REC together for about two seconds.
    4. Release PWR while continuing to hold REC until only two power indicators
       remain lit.
    5. Release REC.

    Verify that PC2 appears in recovery mode:

    ```bash
    lsusb
    ```

    Continue when the output includes `NVIDIA Corp. APX`.
  </Step>

  <Step>
    ### Flash the PC2 Firmware

    Keep the firmware archive on the Ubuntu computer. From the directory that
    contains the archive, run:

    ```bash
    sudo tar -xjvf Jetpack_6.2_nx.tar.bz2
    cd Jetpack_6.2_nx/Linux_for_Tegra
    lsusb | grep -i nvidia
    sudo ./flash_nx_module.sh
    ```

    Keep the G1 powered on and connected over USB until the script reports
    success. The flash takes about eight minutes.
  </Step>

  <Step>
    ### Boot and Verify PC2

    Power off the G1 and disconnect the recovery USB cable. Install the
    replacement NVMe in PC2, close the rear compartment, then power on the G1.
    Wait several minutes for PC2 to boot.

    Connect to PC2 and check the installed release:

    ```bash
    ping 192.168.123.164
    ssh unitree@192.168.123.164

    cat /etc/nv_tegra_release
    cat /etc/os-release
    uname -a
    ```

    JetPack 6.2 includes Jetson Linux R36.4.3 and an Ubuntu 22.04-based root
    filesystem. Use `/etc/nv_tegra_release` as the source of truth for the BSP
    version.

    Follow NVIDIA's current G1 guide for any required post-flash packages and
    power-mode configuration.
  </Step>
</Steps>

## Verify G1 Hardware

After [installing Wendy Agent](../../installation/wendy-agent-unitree-g1/), check
the RealSense camera and other hardware from your development machine:

```bash
wendy device camera list --device unitree-g1-nx.local:50052
wendy device hardware list --device unitree-g1-nx.local:50052
```

Check the G1 in this order:

- Ethernet and Wi-Fi
- USB devices and cameras
- GPU and CUDA
- Unitree services and DDS communication
- G1 app video and image display
- Controlled motion

If a camera app reports that the RealSense is busy, stop only the known service
that owns the camera, then retry.

<Callout type="warning">
  Keep the G1 supported on its gantry and keep the physical remote and E-stop
  with the operator for the first controlled-motion check.
</Callout>

## Next Steps

- [Install Wendy Agent on the G1](../../installation/wendy-agent-unitree-g1/)
- [JetPack 6.2 release information](https://developer.nvidia.com/embedded/jetpack-sdk-62)