When my daughter's recently-acquired iPhone 6 -- from a Craigslist ad -- couldn't hold a charge reliably or for long, I saw the opportunity to prove to myself that I could begin doing phone repairs. So I did just that.
I just replaced a question mark (Can I repair an iPhone 6?) with an Exclamation mark (I can do this!). Feels good to have that first one behind me. Took me double the expected time, just because I had trouble with removal of the battery adhesive strips and the battery itself. Everything else was very straightforward. I used care replacing the connection cables, did the hard reset and tested all functionality. Works great! The battery is re-calibrating now. All in all a positive experience.
Next time I'll have on hand a guitar E-string, as suggested in the Guide, to run behind the battery and pull through the adhesive strip if it breaks off. That should save a lot of time.