what is error code 2002 while restoring iPhone

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, 14, 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.

https://support.apple.com/en-us/HT204770#usb