new battery won't work on x21

[asafbo]

a year ago i bought a new battery from ebay because i thought my battery was dead.

it turned out that my battery was fine and so i didn't use the new one and kept working with the old one.

a few days ago, my battery went dead and replaced it with the one i bought a year ago.
well, the new battery won't charge at all, and the light is alleyways on
yellow.

does any one have an idea, or it turns out that i bought a dead batt ?