1999 t reg central locking not working?

I have just bought a 1999 t reg clio 1.6 auto with 29k on it for the wife, how ever the central locking does not work, so i had a look at the infared and it was full of water and the circut board didnt look great , so i tightend the arial ,to stop any more water !!!!!!!!!!! how do i get it to work , can anyone help