1) Please try to charge the controller firstly if it cannot be used.
2) If you cannot charge the controller, please continuously poke the reset holes of the controller twice to resetting and try again. The LED light will blink after several minutes which indicates the controller is in charging.
3) If you find the button delay when use the Switch controller, please reset the controller and restart the Switch, then the issue will be solved.
4) If you cannot connect the controller with your Switch, please reset the controller first and go to Switch "Setting"--"Controllers and Sensors"--"Disconnect Controllers" to clear the historical connections for Switch, then restart the game console. Then try to pair again. Sometimes Bluetooth cannot connect because your Switch host stores too much Bluetooth memory or AFTER A SOFTWARE’S UPDATE FOR YOUR SWITCH.
5) The default shock intensity of the controller is 100%. You could change this value manually by following the tips in the user manual.