Have you read the trouble shooting? If not click the link https://support.rachio.com/hc/en-us/articles/360003815533-Light-Codes-Rachio-3-#:~:text=Boot%20Error%20One%20-%20If%20the,this%20indicates%20a%20boot%20failure.&text=Boot%20Error%20Two%20-%20If%20the,red%20bar%2C%20contact%20Rachio%20Support.&text=Connecting%20to%20Server%20-%20The%20first,third%20quadrant%20will%20be%20blinking.
First quadrant blinking white, with one light red Boot Error One - If the first quadrant is blinking white with one red, this indicates a boot failure. Unplug the controller, press down on the white button (the directional pad with Rachio symbol) to clear any residual charge within the controller