Earlier quoted context omitted.
They gave him three machines to use for replacing his battery. 1. A machine to melt the glue holding the battery in place 2. A machine to apply even pressure to the new battery to ensure it’s properly adhered 3. A machine to apply heat and even pressure to the entire phone to properly give the phone with a watertight seal. That seems like exactly what I’d expect has to happen to repair the phone back to original spec…
Yeah, but you can do the whole repair without it, if you’re confident that you won’t set the existing battery on fire removing it, and don’t mind some small risk of the new one exploding in your pocket after you sit down, and waterproofing isn’t important to you…
It would be awesome if Apple also offered a lower cost model with an easily replaceable battery (like an old Android), more easily repairable, and not necessarily water proof. But, if there really was a market for that, some Android manufacturer would have something for it. Maybe there is one and I haven't looked.