To remove the battery, I applied acetone on the edges of the battery. Kept it tilted fir a few minutes and started prying with a credit card. Reapply acetone to the edge of the card, pry again, wait a few minutes and pry again. I thought it would be harder than it was. Removing the battery and all adhesive probably cost 30 minutes work.
Absolutely fantastic instructions. Just follow step by step. There will be no surprises. Took about 2-2,5 hours.