Difficult repair? Nope!
Battery was with child. Would only power on with the power cord attached.
The batteries were so swollen, I didn’t have to follow the full guide. I was able to gently pry off the battery adhesive without using the adhesive remover. This, I didn’t have to go through all the steps to remove the speakers. Took about 30 minutes.
Plug the battery cable in before dropping the battery into the computer. The middle cells stuck instantly and were hard to reposition.