I purchased my switch in 2018 when The Mario Odyssey edition came out and finally noticed that it needed a fresh battery. Upon looking up an iFix it video on YouTube about the repair, I decided to pick up the kit and do it myself.
Overall the experience was not too bad. I had a tough time getting one corner tri wing screw out but ended up finally getting it after I went and picked up the big iFix it tool kit to get the job done. Im so glad I needed the extra tools because now I have a great set of screw heads for any other repairs I may need to do :) one thing the repair did not mention and address was that the old battery has adhesive keeping it stuck in the well. A plastic card and spudger didn’t get it to move I had to carefully use a flat head screwdriver to pry it up enough.
My best advise is to take it slow, keep your screws organized and be careful removing the old battery. Once you’re done you'll realize how easy it was and now your switch has new life!