why did you couriered it Back ?
did
eBay India asked you to do so.
Usually you need to click the dispute button and select "product not as described"
and in 99.99999% eBay would have paid you back, and asked you to keep the battery packed in original packing and they'll arrange pickup.
which will never happen, and seller would loose the money and the product.
but as you have shipped the battery back, you are on loss now, ebay will take a stress test, you would eventually drop the case and won't easily
refund you.
I've been on ebay as seller and They kinda harass even the genuine sellers, In my case, guy uploaded pic of old and used flipcover and
ebay slapped me by refunding the money to him, telling me that I am covered, and I would get my product back, which never came, later they took back the money which they included in my account under "seller protection program", which is just a hoax to let people scam the sellers.
they later closed my selling capacity saying my feedback was low, they don't force users to leave feedbacks but duly penalize the honest seller for honesty by accepting false claims. Its a shady place, should be put on as limited use as the paypal is in India, its a curse on eCommerce.
anyway
In your case, who gave you the idea to ship the item back ??????