Troubleshooting Bluetooth connection errors
In most cases, it already helps to restart the Amazon Alexa app on the smartphone. If this is not successful, you can disconnect the Echo Auto for 30 seconds to reinitialize the connection. Other possible solutions are to switch off the Bluetooth connection on the smartphone for at least 30 seconds (Android: airplane mode) and to restart the smartphone completely.
In rare cases it is necessary to pair the Amazon Echo with the smartphone again. To do so, the pairing must first be unpaired and the Echo Auto must be disconnected from the power supply for at least 30 seconds.
https://diysmarthomeplanet.com/echo-auto-setup/#Troubleshooting_Troubleshooting