@jeffsu I understand that totally, I was pretty worried when I first tried this method as well. But the batteries don’t have to be hot, a temperature increase of just a few degrees (my room was about 17C) was already enough. The batteries will get hotter under normal use, so I don’t think it will be very dangerous.
But, yeah, you need to make sure you don’t apply the heat for too long a period, otherwise will indeed get pretty risky! ;)
Ps. to the iFixit team: If you have another MacBook Pro that needs a new battery, I would strongly recommend to try this technique out and document it if it’s successful. It is a lot easier and less risky compared to removing all the sensitive guts of the MacBook and using a strong adhesive, especially for newbies like me. :D
Thank you iFixit for the great battery and instructions! This was by far the most complicated fix I ever did, but it was well worth it!
Just like some people in the comments above, I did not remove the motherboard and all the other parts. After I tried a few (very unsuccessful) other methods, the best working method I found was to use a regular hair blower to warm up the battery for about 20 seconds, after the battery was just a bit warm I used dental floss to cut/saw through the adhesive. When I got stuck again I warmed the battery up again. (I live in the Netherlands and its winter, in warmer areas you might not even need to warm the battery up!) This worked like a charm and after 30-40 minutes all the cells were loose.
The installation of the new battery was a breeze and was done in just a few minutes!
Kind regards, and good luck to those who’re replacing the battery now! :)