Howdy Chris and welcome to CPF!
Yes, as others have mentioned, we can help you better if you'll give us more specific information about your light and battery, however, there are a few things you can check right now that might help your situation.
First, do you have a way to check the voltage of the battery? It's possible that it's not fully charged, and that could be why your light is "dim".
Second, you should check all the electrical contact points in your flashlight and make sure they are clean. Often times a new flashlight will have some gunk (left over from the manufacturing process) on one or more of those electrical connections, and a good cleaning of all the contact points will get things back in working order again. Electrical Contact cleaner is best for this job, but isopropyl alcohol (rubbing alcohol) will usually work in a pinch. Just put a little alcohol on a Q-tip, and use that to wipe off the contact points, which are:
1. Inside the battery tube, a post in the middle of the head of the flashlight (+). Make sure you hold the head UP when cleaning so that liquid doesn't run down into the electronics.
2. Inside the tailcap, usually the end of the spring you'll find there (-).
3. The threads inside the tail cap and on the outside of the battery tube, which is where the "-" part connects, OR the end of the battery tube and the area inside the tailcap where it touches when the tail cap is tightened down.
4. Both ends of the battery, just for good measure : )
Clean those areas well, then make sure your battery is fully charged and inserted correctly, then tighten everything down and give it go. Good luck.
