Replaced iPhone 6 Plus battery but it seems to still drain fast?
So I replaced my iPhone 6 Plus battery back in June. I decided to replace the battery because I got it from my cousin, and the original battery seemed to be draining pretty fast. So after replacing the battery, I still noticed that the battery would drain pretty quickly while using it. From what I can tell, sometimes it'll lose about 10% in an hour from about medium usage. The battery doesn't seem to drain if I'm not using it though. Honestly I'm at a lost as to what to do. All the googling I did hasn't turned up anything useful. It would be very much appreciated if someone could help me find a solution. I'm not sure if it could be the iOS it's on, or a hardware issue. I'm currently on iOS 10.3.3, but I was on 10.3.1 at the time of the battery replacement.
One more thing, while I was putting in the new battery, the battery connector cable got a little bent because it wasn't straight on with the opening. Could that possibly be the issue?
If anyone has an iPhone 6 Plus that can compare their battery life with mine, it would be helpful. Thank you.