Smartphones should not be deeply discharged - the effects on the battery can be devastating. This is exactly what happened to my old iPhone 3GS.
Of course, it's impossible to say whether the 100% was due to deep discharge or some other defect - in any case, it doesn't hurt to keep an eye on your smartphone from time to time and charge it once in a while. After all, apart from the defective iPhone, there hasn't been any other damage: a battery that goes up in flames and is left unattended can cause serious problems. Corresponding videos can be found among others at YouTube.
In any case, the iPhone is so demolished that even repair would be impossible - a case for the recycling bin. At least the materials can still be reused in recycling.
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A pity for the good iPhone. I still own my first iPod touch. 🙂
Yes, it's really good and long lasting - iOS 6.x wouldn't have been good for much anyway, but it would have been enough for the older folks 😉
Oh dear! I didn't know that could happen. One is often not aware that the batteries are a small chemical storage and not maintenance-free or risk-free forever.
So you think it's the deep-discharge effect? Just googled it, and it seems to happen with overload. For no reason Samsung Galaxy S4 batteries bloat.
Is the only reasonable explanation - it was not loaded for a long period of time. Maybe it would have happened otherwise.