Q: iTunes error 53 while updating iPhone 6 iOS to 9.2

Error 53 refers to hardware issues. Info from official support article:

Check for hardware issues

Errors: 1, 3, 11, 12, 13, 14, 16, 20, 21, 23, 26, 27, 28, 29, 34, 35, 36, 37, 40, 53, 56, 1002, 1004, 1011, 1012, 1014, 1667, or 1669.

Your device or computer might have a hardware issue that stops the update or restore from completing.

1. Check that your security software and settings aren't blocking your device from communicating with the Apple update server.
2. Then try to restore your iOS device two more times while connected with a cable, computer, and network you know are good.
3. Make sure that your security software and settings are allowing communication between your device and update servers.
4. If you still see the error message when you update or restore, contact Apple support.

If you still see the error message, check for outdated or modified software.

Have you tried the last suggested step on the website? Take you device to the nearest Apple Store for further diagnostics.

Where did you buy your iPhone? If you have relatives or friends abroad where Apple Store is available send your device to them and ask to take your device to the Apple Store.

Error 53 is a hardware problem related to Touch ID. Most often seen when updating or restoring a phone that has had the screen and/or home button replaced by someone other than Apple. If that's the case, it can not be fixed.

Apple offers out of warranty repair and replacement services in most countries.

Out of warranty replacement.

$299 US, adjust for your location as needed. Be advised that Out of Warranty

replacement is available only in the country of original purchase for the iPhone

being replaced. Since the iPhone you purchased was from your local telco shop, if

they are not an Apple authorized iPhone reseller, the iPhone may be a grey market

item and you may not be able to get Out of Warranty replacement in your country.