Q: iPhone6 dead after update iOS 8.1.3

Try updating your iTunes to the latest level (12.0.1.26).

Use the search function at the top right error 53.

That error code isn't in the apple supported link Resolve iOS update and restore errors - Apple Support

I think the end result is to take the phone to Apple and you may get a replacement phone, I don't remember exactly how the other user fixed error 53, but I do remember them saying they took it to the Apple store.

You can read for yourself when you do the search.

I updated a iPhone 4S and a iPad-4 to 8.1.3 OTA and BOTH needed *Factory Resets* on completion!

My iPad 4 is also in recovery mode after iOS 8.1.3 update from 8.1.2 .... I advise others to wait before doing the update. 

My iPhone 4S is also completely dead after attempting to update to 8.1.3. It cannot even be set back to factory settings, so now I don't know what to do! I get error code 3014, but my host file and internet connection is fine...

Are you sure you're providing the right error code 53? I haven't seen "error 53" at here: iOS: Restore errors 4005, 4013, and 4014 - Apple Support. I think the most efficient way to solve the problem is to put your iPhone into recovery mode and restore it with your iTunes backup. After then, try to do the update again. Good luck!

When I tried to update my iPhone 6 from 8.1.2 to 8.1.3, my device got into a state where it cycled between a screen with an apple on it and a solid red screen. Trying to power off did nothing. This was not how I wanted to spend my afternoon.