1 First of all, if only a part is not lit, you can measure the resistance of each star in turn with a multimeter. One of the light strings has a high resistance, which means there is an open circuit, so it can be removed and replaced with a new light bulb.

2. If the whole string of lights is not on, it means that the main line is open or the controller contact is badly welded, so it is necessary to weld or connect the main line again.

Finally, if the above methods can't be handled, change the starry light.