iPhone shuts down suddenly and stays black
My iPhone 4s now several times suddenly shut down and stayed unresponsive for a long time (1h), at any battery stage.
- I pressed the two buttons for 30sec many times...
- it is not detected in iTunes
- it doesnt display if the charger is plugged or not
- it seems hot after the moment of shutting down.
What would I need to check / replace? I don't know where to start...
What I noticed recently is that the last 20% of battery some times discharge extremely fast. Might it be the battery?