Today, when I got in my MCU-AVS kit was blinking yellow. Without looking at section 2.1.1 of the developer guide I knew it roughly indicated a problem with the Wi-Fi, so I power cycled my board. When it came back up it was still blinking yellow. I happen to notice my echo dot was also blinking yellow also. The yellow blink means that a notification has arrived and when I asked "Alexa, what are my notifications?", Alexa let me know that I can make phone calls through her.