Does the battery indicator light go amber when you have the charger connected and turned on.
If not it could either be a faulty charger unit or faulty charging circuit in the notebook.
Does the notebook work correctly with the charging unit plugged in and switched on? If so it indicates that the AC charging unit is working. If not it is either a faulty charging unit or faulty power circuit in the notebook.
Had a similar problem with my tablet (not same brand). Must have been in the warehouse for a long time, the battery was completely flat. Left the charger connected and switched on without the tablet being on (so all the power is sent to the battery) and after about 1-2 hours it suddenly kicked into life and started charging. Took another 3 hours to fully charge been alright ever since.
If that doesn't work suggest you take it back under warranty as it is either a faulty battery or notebook battery charging circuit..