Holy smokes. I really enjoy taking things apart and consider myself reasonably handy with things. Doing these things help me relax a bit. But this was intense!

I skipped one critical step which was to drain the battery. Like a few others, I have an iPhone 6 battery that was very difficult to remove. Both adhesive strips broke before I could take them off. So I used a blow dryer and then tried to pull it out. The battery combusted and left a mark on my hardwood floor. It was incredible. The whole phone turned into smoke and the house too. I'm surprised my smoke detector didn't go off. The phone remained very very hot for another 10 minutes. Just for giggles I decided to wipe off the phone and tried the new battery in. Everything worked just fine, I couldn't believe it!

Anyways, I don't recommend trying this unless you are really really handy with tools. Especially on the iPhone 6 which from reading on here seems to have an extremely sticky battery.