Sticky strips are to iPhone battery repair, what Kryptonite is to Superman
Ray Dzek -
iPhone 6s battery life had degraded considerably. Apple stores have no available appointments, and blogs are full of comments where the Apple stores don't have batteries to install anyway.
Overall the repair went OK. Right out of the gate, the driver tips that came with the kit were of poor quality and did not fit the internal screws. I was able to find one of my own drivers that fit. The adhesive strips that hold the battery in place are deceptively strong. I was able to get one out cleanly, but not the other. A heat gun may have helped but was not available. It took gentle and patient prying to get the old battery out.
Take your time with the adhesive strips in the removal process. Do not yank on them. Slow, patient, firm pressure is the key. Do not tug or yank to get them to come out. Slow, steady pressure is the key.
Make sure you have a well lit, and clean surface. The screws that come out are itty bitty. Lay them down in the same order you removed them. Be careful when removing the screen that you do not rip the ribbon cables. Oh, and this is a biggie—the video that is recommended to watch does not even mention the installation of the replacement gasket material that comes in the kit. You have to be sure to clean off the old gasket material first. Then remove one side the gasket, plastic "sandwich," lay it over the phone (And there is no indication of orientation either so I had to just figure it out). And carefully using one of the plastic spudgers, adhese the gasket to the case again before re-assembly. Again, a bright light source and patience are your friend.