The most common cause of LED strip lights failing to work is the loose connection between the LED strip and the controller. Before you call the manufacturer or return the product for replacement, you can test and solve the problem on your own. 1. Check if the power wire and signal wire are connected well. 2. Check if the power supply is steady. 3. Check if the controller is powered on. 4. Reset the controller to factory settings. If your LED strip light is still not working after these steps, then you should return it for replacement.