Used this guide to pop the heat sink and scrape off the old thermal paste. Cleaned and re-applied with new paste, hopefully leading to better thermal performance. One thing I noticed is that the heatsink doesn’t cover the second module (presumed to be the integrated GPU) next to the CPU? Perhaps this is why thermal performance is so abysmal on these little guys.
Completed on my MBP, the original battery has had around 260 cycles now. Still love this little guy, so I’m glad I’m able to get the battery swapped and feels like new again! In the process also cleaned/re-applied the thermal paste on the CPU and swapped out the SSD!
Just finished replacing the battery on my MBP. The original battery module was bulging and warped the bottom case of the laptop along with making the trackpad not work well at all (unable to click anything). Very thorough guide, I had no issues with disassembly. I even managed to sneak in a heat sink disassembly to clean and remove the old thermal paste. Unbelievable how much thermal compound was in and around the CPU and GPU!
After thoroughly cleaning I just re-spread new thermal paste on the CPU and GPU surfaces, screwed everything back and called it a day! Thanks iFixIt! Everything seems to be working well now with much better temperatures, lower case replaced as well, trackpad now works and AFAIK all I/O ports are functional.