A friend took his iPhone 6Plus scuba diving with a not so waterproof case.
Was able to get the battery out and replace it...sadly it did not charge. The tool kit is amazing...every tool you need to make it go smoothly. I had watched a video with a 10 year old showing me how to open the case with an 11/16" nail. It worked, but once opened you really need the tools to finish one-handed.
Be verry, werry careful opening the case to 90 degrees...the strip is easily tearable
Seriously, read everything and watch the videos before starting to remove the battery. Those sticky
strips of adhesive are a total pain, especially when water damaged. I propped it up and blocked it from both sides so that I could use both hands. At least we gave it every shot to save it, and now I have an iPhone 6 Plus in the morgue and intend to strip it down and learn every piece of it for future operations :)