Antwoord op "My presenter is about one year old. It is not working; has new batter"What is not working? It has a transmitter for presenting. And an independent laser. Is the laser at least working? And what have you done to confirm that your new batteries are at full power and not to blame? In my presenter, there are two batteries, both AAA. If you get the laser to work, then you have proof that you found two good batteries and have entered then in the correct orientation. It is highly unlikely that both the transmitter and the laser should fail at the same time, unless some external influence like damp or heat (kept in a car) came into play.