# Troubleshooting

### Changing the Baud Rate (Permanent Fix)

#### 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**

3. 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

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)

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

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

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.

***

If you’re still experiencing issues after following this guide, open a support ticket in Discord with:

* A photo of your wiring
* A screenshot of the error
* Your firmware version


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