Original post by: Thomas Bladen ,
I had the same problem earlier today. A while back my friend fixed my phone screen as it had broken and when he did this, he must have moved some components around without realising. This caused the phone's battery to stay on the same % until it had either been charged or restarted. Therefore I had to guess whenever it was going to go out of battery and when it did go out of battery, I would charge it up and if I went on the phone straight away, it would continue to restart so I had to leave it for a few minutes. However today I experienced something new, once my phone had gone out of battery I tried turning it on, this didn't work and when I plugged it into a charger it constantly restarted. To fix this, I held down the power and home button for about 20 seconds until the iTunes screen came up. I had iTunes ready on my computer and as soon as this happened I clicked 'restore'. ITunes began to 'extract the software' and the it told me it couldn't restore the iPhone. So the second time I did this I clicked 'update' instead. This meant that it would need to restore it after it updated it but once again it failed to restore it. I tried turning the phone on whilst plugged in after all this and it actually worked!