If your battery connections are corroded, you can remove the battery, and carefully wipe the corrosion from the battery socket inside the camera with a damp (not wet) paper towel. If the problem does not resolve, you can try lightly sanding the spring inside the camera. However, if you choose to sand it, you need to remove any metal dust from the camera before you re-install the batteries and power the camera on. If your camera still doesn’t work, you can try replacing the batteries themselves.