look in my profile ;-)
Without looking at the battery cant say whats up with it, But most common cause is water has got in under the sleeving and the cells & protection circuit have corroded. Common problem if you google it.
I can supply you with a new one but should you prefer to post me your battery for me to check it over first I can do that for you too.
BUT battery will cost approx same price for a 4.4Ah, uprated capacity more.
How old is it? it may still be covered under its guarantee.
Smudge