Battery in my laptop was no longer holding a charge. It was the original battery bought with the computer which was purchased 6 years ago. The computer still worked fine it was just the battery that was the problem.
Followed the iFixit instructions. The repair was quite easy actually. It was a little difficult to disconnect the battery connector from the logic board because as you pull the battery up, the connector, which is attached to the battery with some glue starts to pull away from the battery and it was unclear if I was tearing the battery open by accident (don't worry, you are not). Once I realized it wasn't harming the old battery, I was able to gain better access to the logic board connector and disconnect the battery.
The battery connector may be hard to get to when removing the battery. A gentle pull with ease the connector off the back of the battery just enough to give you better access to the logic board connection. When installing, also pull the battery connector off the back of the new battery just a little to make installation easier as well. Once the battery is in, give it a gentle nudge to help the adhesive on the connector and battery to reseal, then replace the screws.