What should I do if the controller won't connect?

First, ensure the back gear of the controller is in the correct position, then press and hold the pairing button for three seconds until the indicator flashes quickly and the controller enters pairing state. For dongle connection, unplug and replug the receiver into the USB port; for Bluetooth, unpair the device in Bluetooth settings, toggle Bluetooth off and on, and reconnect. (Page 8)