> For the complete documentation index, see [llms.txt](https://docs.champcheats.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.champcheats.com/dma-docs/makcu/troubleshooting.md).

# Troubleshooting

#### Changing the Baud Rate (Permanent Fix) <a href="#changing-the-baud-rate-permanent-fix" id="changing-the-baud-rate-permanent-fix"></a>

**How to Change the Baud Rate**

1. While MAKCU is running, press the **LEFT button 4 times within 2 seconds**.
2. The LED next to USB 1 will flash to show the current baud rate:

* **4 flashes = 4 Mbps**
* **1 flash = 115k**

1. Press the button again to cycle between baud rates.

This is the **only way** to permanently save the baud rate setting.

If you see 4 flashes on boot but need 115k:

* Press the LEFT button 4 times within 2 seconds to switch.

***

#### Ignore Windows Baud Rate Settings <a href="#ignore-windows-baud-rate-settings" id="ignore-windows-baud-rate-settings"></a>

Do NOT change the baud rate in Windows Device Manager.

* Windows settings have **zero effect** on MAKCU’s actual speed.
* MAKCU manages its baud rate internally.
* Windows baud rate settings are completely ignored.

You can safely leave them as-is.

***

#### \[handle\_unknown\_command] \[ERROR] (Inside AIO Tool) <a href="#handle_unknown_command-error-inside-aio-tool" id="handle_unknown_command-error-inside-aio-tool"></a>

If you see this error:

You are on **V2 firmware**.

To fix:

Option 1: Reflash the firmware using the flashing guide. Option 2: While MAKCU is running, press the **LEFT button once** to switch baud rate. This change saves permanently.

***

#### Mouse Not Moving or Test Not Working <a href="#mouse-not-moving-or-test-not-working" id="mouse-not-moving-or-test-not-working"></a>

If the mouse is not moving during testing:

1. Check the list of known working mice: <https://pastebin.com/ukRq383f>
2. If your mouse is not on the list, assume it is incompatible with MAKCU.

Recommendations:

* Swap to a confirmed working mouse.
* Avoid unbranded AliExpress / Temu mice.
* Use known brand gaming mice.

***

#### “Failed to write serial” Error <a href="#failed-to-write-serial-error" id="failed-to-write-serial-error"></a>

If you receive a “Failed to write serial” error:

1. Make sure you are using the SECOND PC.
2. Swap USB ports.
3. If the issue continues, replace the USB-A to USB-A cable.

Low-quality cables are a common cause of this issue.


---

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