I followed the guide here and successfully replaced the battery on my 8+. Disassembly was a breeze, but the reassembly is slow and tedious since you have to be very careful reconnecting cables etc. By far the hardest part was getting the old battery out. I could not grasp the edges of the old adhesive strips at all. But the dental floss technique work well, altho it was slow. I was able to the old battery out and removed the old adhesive strips from the inside of the case. Reassembly is greatly aided by lighted magnification; the screws are beyond tiny! Once reassembled the phone booted and showed 60% capacity. I charged it well past 100% and then left the phone off the charger for more than 24 hours to spend the battery out. Then recharged again to 100%. Now the phone lasts beyond all day. Great repair.