Error while trying to restore iPhone 6 Plus Error 40
I bought this phone from eBay to try to repair it. I replaced the battery , charging port and the screen. The phone turns on and all I see is a lit black screen. I plugged it into the computer and the computer recognizes it and iTunes says that the phone is in "recovery mode" and it needs to be restored and updated. I've tried to restore and update it, but every time I try to do that, the apple logo comes up and the bar and after a few minutes I get this message:
"The iPhone could not be restored. An unknown error occurred(40)."
What could be the issue? My iTunes is up to date.