Brand new phone battery. Not turning on at all.

So i had to replace my phones battery because it began to swell, I got myself a kit and the new battery arrived today. I followed a guide to take apart the phone without a hitch, and removed the old battery and replaced the new one. Put my phone back together and go to try and turn on the phone and nothing. No vibration, no screen light up.

I'm quite confused because the battery is brand new with no damage to the connectors or anything, I plug the phone in to charge it to see if maybe it needs juice or something and it gets warm but still nothing. I'm tempted to buy a new phone battery assuming the one I received is defective, but I wonder if I should just wait and see if the phone eventually turns on. I would absolutely love some expert advice or input. Thank you!