The iPhine "iPhone" could not be restored. An unknown error occurred (2009)

See this Apple article: iOS update and restore errors

iOS update and restore errors – Apple Support (UK)

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Check your USB connections

If you see error 4005, 4013 or 4014, use these steps.

If you see one of the errors below, check your USB connection, USB cable, USB port or computer:

• 13, 1600, 1601, 1602, 1603, 1604, 1611, 1643-1650
• 2000, 2001, 2002, 2005, 2006, 2009
• An error that includes "invalid response"

Here's what to check. Try again after each step:

1. Use the USB cable that came with your device. If you don't have it, try a different Apple USB cable. 
2. Switch to a different USB port on your computer. Don't plug into your keyboard.
3. Switch to a USB port on a different computer.
4. If you still see the error, check for other USB issues, check your third-party security software, then check your hardware.

If you still see an error, contact Apple Support. 

See this support article:--> iOS update and restore errors and click on th error code on the left.

If the issue persists, I suggest that you contact Apple support directly, using this link:--> Contact - Official Apple Support

Regards

Giulio