Chosen Solution

I bought a replacement battery on eBay and I tried it in my phone but it didn’t work so I put the old battery back in and it worked fine. They sent me a new one but I’m worried that one won’t work too. Does anyone know where to get a good battery replacement. Or if I’m doing something wrong.

Get it from Apple: https://www.apple.com/support/iphone6s-u

@blkim1104 if the old battery works but your “new replacement” does not, I am certain you have a dud. Get your replacements from here. It is more expensive than ebay but you can at least count on the quality and guarantee.