I was scammed one time when I bought a portable speaker. It looks nice and 100% working but when I used it the battery isn't working. So the next time I bought another item I checked the dealer and read the reviews carefully.
But you have received the item, the battery is defective as a consumer you must know that it's part of the risk of purchasing something online. And before doing that, check if the seller is reputable and has a good history with successful purchases.
If you have time and you can go to the mall, do it but if you are a busy person and you think that online shopping will save you time, think of its consequences like your experience.