I had a huge amount of difficulty removing the battery during this repair. The adhesive is really strong, the suction cup doesn't stick to the battery very well and if you lever it out you run the risk of puncturing the battery. It's also really difficult to pull up on the battery while holding the phone down, especially because you want to avoid touching the circuits.

Eventually I succeeded and everything seemed to work but the next day the phone wouldn't switch on. I think maybe the adhesive remover got somewhere it shouldn't have. If I could add something to this guide, it would be "once battery is removed, allow phone to sit for 30 mins to ensure all adhesive remover has evaporated". If I was allowed a do-over I would try to heat the adhesive instead. Or use the string trick. I'm switching to an iphone now because apparently they don't glue their batteries.