Fixing the Nano Duo Screen Stuck on the LONGER Logo
Nano Series

Fixing the Nano Duo Screen Stuck on the LONGER Logo

January 14, 2026
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If your Nano Duo screen is stuck on the LONGER logo during startup, the issue is usually related to corrupted or incomplete firmware. Fortunately, the problem can typically be resolved by reflashing the firmware using the official recovery method.

This guide explains the complete process step by step in a beginner-friendly format while preserving the original flashing procedure and settings exactly as required.

Table of Contents

  1. What This Guide Covers
  2. Quick Answer
  3. Why This Process Matters
  4. Before You Start
    • Requirements
    • Precautions
  5. Step-by-Step Tutorial
  6. Common Problems and Solutions
  7. Tips for Better Results
  8. Frequently Asked Questions
  9. Final Thoughts

What This Guide Covers

This tutorial explains how to recover a Nano Duo machine when the display freezes on the LONGER startup logo.

You will learn:

  • How to prepare the firmware flashing tool
  • Which firmware file to use
  • How to configure the correct flashing parameters
  • How to erase and reflash the firmware safely
  • What to do if the process does not complete successfully

The instructions below preserve the original operation sequence and parameter values exactly.

Quick Answer

If the Nano Duo screen stays stuck on the LONGER logo during startup, reflash the firmware using flash_download_tool_3.9.5.exe, select ESP32-S3, load firmware_grbl.bin, set the firmware address to 0x0, choose the correct COM port, set BAUD: 912600, then click ERASE followed by START. After the process displays FINISH, restart the machine.

Why This Process Matters

Firmware controls the startup and operation of the Nano Duo. If the firmware becomes damaged, incomplete, or corrupted, the machine may fail to boot normally and remain frozen on the LONGER logo screen.

Reflashing the firmware restores the machine’s core system files and allows the Nano Duo to start correctly again. Following the official flashing sequence carefully helps avoid additional startup issues or failed firmware recovery attempts.

Before You Start

Requirements

Before beginning, prepare the following items:

  • Nano Duo machine
  • Windows computer
  • USB cable compatible with the machine
  • flash_download_tool_3.9.5.exe
  • firmware_grbl.bin firmware file

Follow official machine specifications or instructions if additional drivers or accessories are required.

Precautions

Before performing firmware recovery, keep these important safety notes in mind:

  • Do not disconnect the USB cable during flashing.
  • Do not power off the machine while firmware is being written.
  • Make sure the correct COM port is selected.
  • Double-check all parameters before clicking START.
  • Close unnecessary software to reduce communication interruptions.
  • Use a stable power source during the process.

Incorrect flashing parameters or interrupting the process may prevent the machine from booting properly.

Step-by-Step Tutorial

Step 1: Prepare Tools

Action

Use the flash_download_tool_3.9.5.exe tool.

Expected Result

The firmware flashing tool is available and ready to launch on your computer.

Important Notes

Ensure the tool is fully downloaded before opening it. Running incomplete or corrupted files may cause flashing errors.

Step 2: Preparing Firmware

Action

Prepare the firmware file:

firmware_grbl.bin

Expected Result

The firmware file is ready to be selected inside the flashing tool.

Important Notes

Do not rename the firmware file. Keep it in an easy-to-find folder on your computer.

Step 3: Open the Flash Tool

Action

Open the flash_download_tool_3.9.5.exe tool, select ESP32-S3, and click OK.

Expected Result

The tool enters the main flashing interface homepage.

Important Notes

Selecting the correct chip type is critical. Ensure ESP32-S3 is selected exactly as specified.

 

Step 4: Configure Firmware and Flash the Machine

Action

After entering the homepage:

  1. Click the three dots in the middle.
  2. Find the prepared firmware and open it.
  3. Change the firmware to: 0x0
  4. Select the COM port corresponding to the machine's port number.
  5. Select BAUD: 912600
  6. Click ERASE and wait for the status to complete.
  7. Click START and wait for the status to display FINISH.
  8. Power off and restart the machine.

Expected Result

The firmware flashing completes successfully, and the machine restarts normally instead of remaining stuck on the LONGER logo.

Important Notes

  • Wait patiently during both the ERASE and START processes.
  • Do not disconnect cables or close the software during flashing.
  • The process may take several minutes depending on the computer and connection stability.
  • If the status does not display FINISH, repeat the procedure carefully.

Conclusion

That’s the complete procedure for resolving the issue where the Nano Duo screen is stuck displaying the LONGER logo. The success of this process mainly depends on accurate parameter configuration and following the flashing steps in the correct order. As long as each setting is verified carefully and the sequence is strictly followed, the firmware recovery can be completed smoothly and safely.

Common Problems and Solutions

Problem Possible Cause Solution
Tool cannot detect the machine Incorrect COM port selected Reconnect the machine and select the correct COM port
Flashing stops midway Unstable USB connection Use a stable USB cable and avoid moving the cable during flashing
Screen still stuck on LONGER logo Firmware flashing incomplete Repeat the flashing process carefully
ERASE does not complete Communication interruption Restart the tool and reconnect the machine
START button fails Incorrect firmware configuration Verify 0x0, ESP32-S3, and BAUD: 912600 settings
Machine does not restart normally Firmware corruption remains Repeat the entire firmware recovery sequence

Tips for Better Results

  • Use the original USB cable whenever possible.
  • Avoid USB hubs during firmware flashing.
  • Keep the firmware file in a simple folder path such as the Desktop.
  • Close background programs that may interfere with serial communication.
  • Verify every setting before clicking ERASE or START.
  • Restart the computer if the COM port is not recognized properly.

Frequently Asked Questions

1. Why is my Nano Duo stuck on the LONGER logo?

This usually happens because the firmware is corrupted, incomplete, or failed during a previous update or startup process.

2. What firmware file should I use?

Use:

firmware_grbl.bin

Do not modify the file name unless official instructions specifically require it.

3. Which chip option should I select in the flashing tool?

Select:

ESP32-S3

Choosing the wrong chip type may cause flashing failure.

4. What baud rate should I use?

Set:

BAUD: 912600

Do not change this value during the procedure.

5. What does changing the firmware to 0x0 mean?

The firmware address must be configured as:

0x0

This ensures the firmware is written to the correct memory location.

6. What should I do if the flashing process freezes?

Wait several minutes first. If there is still no progress, restart the tool, reconnect the machine, and repeat the flashing process carefully.

7. Can I disconnect the machine during flashing?

No. Disconnecting the machine during flashing may corrupt the firmware further and prevent proper startup.

8. What should I do if the machine still cannot boot after flashing?

Repeat the firmware recovery process and carefully verify all settings and parameters again.

Follow official machine specifications or instructions if additional troubleshooting is required.

Final Thoughts

Fixing a Nano Duo screen stuck on the LONGER logo is usually straightforward when the firmware recovery process is followed correctly. The most important factors are selecting the correct parameters, using the proper firmware file, and performing each step in the exact order.

By carefully following this guide, users can safely restore normal Nano Duo startup operation and reduce the risk of additional firmware issues in the future.

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