The warranty is 28 days, so thats out if the battery is 6 weeks old.
There is one more thing that you could try, just in case the battery is actually
flat but just not connecting with the charger. Use a straightened out paper clip
or something similar, slide it down the side of the centre pin on the battery and
then just gently (really gently) nudge the centre pin back and forth a couple of times.
Sometimes this moves it just a mm or two and allows for it to connect with charger.
If that doesn't work then I wouldn't know what else to suggest