iPhone not starting

Trying to fix an iPhone 5S.

Phone was showing apple logo on start-up - nothing else after waiting over half an hour.

Help docs online said to connect to computer, launch iTunes, hard reset the phone.

Did this. When prompted, selected to Update the phone.

Waited over an hour while 2.5GB downloaded.

Nothing happened. Help docs said to hard reset the phone again, which I did.

iTunes prompted to Update the phone. It said if it can't update the phone I'll have to restore it (ie. lose everything).

It went through a couple dialogue boxes.

An error appeared (Error: (-18)) and it said that it could not update the phone.

I clicked 'ok' and the message said it was restoring the phone.

At this point I quickly unplugged the phone - it should have warned me that it was about to restore, not just gone ahead. Also - why doesn't Apple explain what error -18 means? And why the phone can't be updated? Surely there must be some way to recover everything from the phone's storage?

Anyway, having disconnected the phone I now hard-reset the phone. It goes through the apple logo and then to the screen that prompts me to connect to iTunes.

I've restarted a few times and get the same result.

How do I recover all the data from the phone from here?

What *exactly* is going on with each of the above steps? What would be the first step in a restore (if indeed it commenced a restore)? Would it render the data unrecoverable?

Imagine I was head of forensics at the state police department - are you telling me there *really* is no way to recover the data? Hit me with any option, no matter how un-ordinary it is.