Answer to: Why won't phone stay on unless plugged in?I agree with this answer and only wish I had found it earlier, as I had the same or similar fault, mine started with the apple logo going on and off, and going into restore mode didnt help and constantly failed. This fault then went on to the phone only working when plugged into the charger, it did however boot normally but went off again as soon as it was disconnected, so obviously a battery problem would be a good guess. I purchased a new battery and the phone is now working as it should. A final word of warning though, having charged my other new phone with the same charger I got the flashing apple logo, luckily removing the charger and rebooting the phone sorted it, I would recommend not using the same charger again because it nearly destroyed my other phone as well. A new charger is cheaper than another phone.