# Troubleshooting

Common problems and how to solve them. If your case isn't here, reach out via the contact form on the web.

## The dongle won't power on

- Check the battery is correctly seated (polarity).
- Confirm the battery is a **rechargeable Li-ion 3.7V** cell in **16340** or **18350** format (not the primary 3V CR123A).
- Plug in the USB-C cable: if it's charging you should see the lightning bolt icon on the OLED.
- If the dongle shut down due to inactivity, press the button briefly to wake it in Multiboot.

## OLED is invisible / flickers

- If it flickers **when plugging USB**, check the cable and power supply. Outside flashing or an update, you can shut down by holding the button for 3 seconds, release it, then press briefly to power on again.
- If it never displays anything, check the screen isn't physically damaged.

## The GBA does not receive the menu

- Make sure the Link cable is properly seated on both ends.
- Start the GBA holding **Select + Start** until the Game Boy logo stays still.
- Leave the dongle in **Multiboot**. Short presses cycle through **Multiboot → GBA → Online → Multiboot**; transfer starts automatically when a ready GBA is detected.
- A cartridge is not needed to receive the menu. See [Getting started](doc:getting-started) for the complete procedure.

## Wi-Fi won't connect or drops

- Check from the GBA itself (**Settings → Wi-Fi**) that you can see your network.
- Verify the password.
- If your network is **5 GHz only**, the dongle won't see it: the ESP32 only supports 2.4 GHz.
- If it connects but drops mid-download, try moving the dongle closer to the router.

## The game does not connect in Online mode

- Check that the game uses the CanoFlash SDK and that Wi-Fi has Internet access.
- You can select **Online** with the button before pressing **Connect** in the game. The SDK handshake is also detected from **GBA** and **Multiboot**.
- Changing modes keeps Wi-Fi on. Pressing the button while in Online closes the session and returns to Multiboot; do not use it to refresh a running match.
- If the dongle shut down due to inactivity, wake it with a short press and reconnect from the game.
- For API key, room or reconnection errors, see the [SDK troubleshooting guide](/en/docs/sdk/troubleshooting).

## Cartridge verification fails

- Make sure the cartridge has the supported chip (AMD/Spansion S29GL256).
- Clean the cartridge contacts with a cotton swab and isopropyl alcohol.
- Retry the download: a momentary bad contact can break verification.

## Cartridge not recognized

- The dongle shows the chip ID it reads. If it doesn't match `0x227E`, that cartridge is not supported.
- Cartridges with Macronix, Sharp or other chips are not currently supported.

## My save doesn't show up in the cloud

- Confirm you have uploaded the save from **Save Manager** on the GBA, not just saved on the cartridge.
- Refresh the **Saves** tab on the web.
- Check Wi-Fi and retry the upload from the GBA. Authentication renews automatically; changing mode with the button does not force a renewal.

## How to recover a dongle that won't authenticate

If the web tells you the dongle isn't authenticated:

1. Check that the device serial number (`CFX-XXXXXX`) matches the device linked in your panel.
2. If you have updated the firmware, check the Wi-Fi connection and use the official recovery procedure if the problem persists.
3. To restart, hold the button for at least 3 seconds to shut down, release it, then press briefly to power on. This keeps your configuration; it is not a factory reset.