Battery was lagging, and phone was not working very well. It would not hold a charge for long. Not sure if the problem is fixed as I am still charging the new battery. Fingers crossed!
It was okay. I pulled the first adhesive strip out successfully, but the second one broke and I could not get to it to start again. I tried everything and this is where I burned up a lot of time. It was extremely frustrating to get the battery off because I had to be careful not to damage the phone while trying different tricks. Those adhesive strips are super strong!
I used dental floss, a credit card, and a hair dryer to get the battery off. Watch LOTS of different videos to get all the tips. Not all the videos prepare you, so one is not enough. Also, I wish I would have watched more of the videos before I stuck the new battery on, because it was slightly off a bit and then I struggled for another 15 minutes to get the battery connected to it's port. So connect that first, and then set the battery into it's place. I had to fudge with that for a while until it actually lined up and I could put all the screws in. It was almost a total fail. Whew......