Ha! Just going through the same process with my 3 month old I-phone 6S. Battery started discharging itself and getting hot. Didn’t take a full charge. Was answering a call from Andrew when my ear started getting hot followed by call cut-off and a prompt message on screen advising phone shutting down for overtemperature protection of battery. Straight into town where I stood my ground for a loan-phone whilst new phone was away being tested. Alison’s I-phone (bought same date as my old one) is also expiring but may go Android for her replacement. A lot of energy in a mobile phone battery just waiting to escape (along with the smoke) so you have to pay a bit of attention when they start getting warm. Cheers.
Derb. 2017 Colorado LTZ 4 x 4 Auto. 2014 Southern Star 720 and 1980 Zephette 340. 2 x 100 a/h AGM. 3 x 150w solar. Ctek D250S-Dual controller/MXS15 charger.172L fresh/grey. Diesel heat. RMD8555 fridge.