Hi @kirathelemon ,
Did you buy the battery replacement kit from ifixit?
If so, [https://help.ifixit.com/article/49-return-policy|contact ifixit] (scroll to bottom of page to find Contact link) and tell them about the problem.
If not contact the seller and tell them.
Looking at the images in the ifixit [guide|383] guide, the battery doesn’t appear to be resting on the motherboard