Q: plz help me.i can't restore ipsw 9.3.3error 56 for iphone6..       

If you see one of the errors below, you might have a hardware issue:

• 1, 3, 10, 11, 12, 13, 14, 16
• 20, 21, 23, 26, 27, 28, 29, 34, 35, 36, 37, 40, 56
• 1002, 1004, 1011, 1012, 1014, 1667 1669

Here's what to check:

1. Make sure that you have the latest version of iTunes.
2. Check for issues with third-party security software.
3. Make sure that your USB cable, computer, and network are reliable. Then try twice more to restore your iPhone, iPad, or iPod.
4. If you still see the error message, you can check for outdated or modified software or contact Apple Support.

Information above is from this support article > Get help with iOS update and restore errors - Apple Support

Can you connect to your computer and do a restore in iTunes with a new download?