How can I start my Laguna DCI?

Hi, The battery went flat on my 05 laguna. I charged the battery overnight and the car started fine and all was well for a day or two. Now the car will not start. The battery is fine, I put the key card in but nothing happens. I have been told it could be the card reader is faulty or the steering board is faulty. The car is totally immobilised! Any Ideas would be appreciated! Thanks