Well, you see, it's all about finding the right tools and materials. For led Christmas lights, you'll need a soldering iron, some solder wire, and some flux. You'll also need a pair of wire cutters and some electrical tape. Start by taking off the outer casing of the light strand and removing any burnt out bulbs. Then, using the soldering iron and solder wire, you can repair any wires that have been damaged. Finally, use the electrical tape to cover the repaired areas and voila! You've got working led Christmas lights again!