Nissan Micra Central locking problems

I recently bought an 04 plate nissan Micra and tonight was unable to unlock the car with the electronic key. I had the battery changed and it still did not work... after much investigation i found the manual key lock on the passenger door which allowed to me to get in but am concerned as to why my key failed even after changing the battery. Since i bought the car everytime i have got in there has been a small red light flashing on the dashboard..its the shape of a car with a key in the middle... i was told this meant the car was unlocked with the engine turned off but am now thinking it may be trying to tell me something is wrong with the central locking... i didn't get the book with it and cannot find one online..can anyone help!?!?

If its that new, is it still under warranty?

yeah it is...still got a year and a half of the warranty. I will be taking it to the garage tomorrow but was hoping for some words of wisdom first... so i know what to expect really.

Must be something wrong with either the key or reciever...
Not much help really!
Just dont let them fob you off, it should be completly free as its a manufactures fault, not wear and tear, and if its an inconvenince, ask for a courtesy car, they can only say no!
Try asking them to throw in a handbook too

cheers for that. They WILL be giving me a handbook...surely that should come when you buy a car...even when its 2nd hand!! plus theres no way i'd let them fob me off with something so major... it could leave me stranded! Cheers anyway.