The first step is to check whether the circuit is good and connected.2. Check whether there is any current or voltage in the circuit with an electric pen. If there is no problem in the circuit, then check the led lamp driver.3. After energizing the led lamp, the bulb still does not work. You can use a new driver to check whether it is working.Switch contact fire line, zero line contact electrical appliances, professional electrician will not make this mistake.