Early 2011 MBP Replaced battery + Reset SMC Shuts off randomly

Hey!

So I replaced the battery in my Early 2011 Macbook Pro. After replacing it, I noticed that the new battery wasn't holding a charge like it should. So, I reset the SMC with the "I can't take the battery out" method. After that I experienced the same issue along with the macbook randomly shutting down or sleeping. I then tried the "Removable battery" method of resetting the SMC. I opened up the bottom and disconnected the battery, the whole shebang. Still shutting down randomly.

After booting up from resetting the SMC, it will stay on for about five minutes and the fans will ramp up until they're running at full capacity and then the whole computer will shut down and not attempt to restart itself.

Help?