Connector different from iPhone 8X

There is no iPhone 8x or do you mean the battery or your phone is different than what the battery was intended?

Look at this image which is your phone?

And then look at the iFixit battery it should tell you which phone it's intended for.

If it's correct, look at the battery connector both the battery and the phone are any of the contacts damaged or the plastic pushed in blocking the connection.

@pleasedont46099 iPhone 8 and iPhone 8 Plus share the same battery connector. Physically, the 8Plus is a larger battery and will not fit a regular iPhone 8. Double check your phone to figure put what model you have. You can use this site for that Of course, you can also try that by the battery connector

If in doubt, take some well focused pictures of the battery connector and your replacement battery (if you still have the old battery, a picture of that as well) and post those with your Question. That way we can see what you see and hopefully find out what's going on with this. Adding images to an existing question