Unexpected shutdown of iphone
After putting in recovery mode and then restring, I get: "The iPhone “iPhone” could not be restored. An unknown error occurred (21)."
Question marked as
Could be a hardware malfunction.
iOS update and restore errors - Apple Support
If you see one of the errors below, you might have a hardware issue:
1, 3, 11, 12, 13, 16
20, 21, 23, 26, 27, 28, 29, 34, 35, 36, 37, 40, 56
1002, 1004, 1011, 1012, 1014, 1667, 1669