Hi kirtong the first thing is try to establish what flattened the battery,eg did you have lights on?? or has the battery just gone completly dead on you ,they do go all of a sudden,and as your car is 04 reg and if the battery is the original get it tested as i should say your battery is duff but still has enough power to opperate the alarm system...
I have a battery charger, would it be ok to just remove and charge?
Would code's need re-entering etc??