Ah Ha
Managing the user expectation of ludicrously thin phones because its pretty and the laws of physics is always going to be tricky, actually I like the technical thought that came up with this last gasp solution to imminent battery failure but the poorly thought out marketing decision to keep it hidden was about phone sales. I find it best to have a grown up discussion about obsolescence and let your customer know they are making a trade off between usability and prettiness, in Hi Reliability environments we do this all the time and some times cheap and nasty is best, but there's no excuse for deliberately failing to provide a user repair path for a consumable item like a battery!