When it comes to fixing lights on a pre-lit Christmas tree, there are a few steps you can take. First, check the power cord for any signs of damage or wear and tear. If the cord is damaged, you may need to replace it. Next, check the bulbs to see if any are burned out or loose. If you find any bad bulbs, replace them with new ones. Finally, check the fuses on the light strand and replace any blown fuses. With these simple steps, you should be able to get your pre-lit tree back up and running in no time!