Your VR300 is telling you that it cannot connect to the network you previously set up. Make sure that the VR300 can receive the Wi-Fi signal from your router in its current position, and that your Wi-Fi connection is switched on. (You can test this using another Wi-Fi enabled device.)
If this is not sufficient, it is recommended to use the "three-finger salute" (firmly press the green start button and the opposite bumper side simultaneously for approx. 6 seconds) and then re-integrate the robot into the WLAN.
Do NOT use force to push on the start button. A light press is enough to activate it.