Error 1671 after screen and battery change

Hello,

I had iphone 6 plus that had cracked screen. I replaced the screen but once I put everything together, I was unable to close it because the battery was bubbled up. I ordered a new battery and when I changed it the apple log come on for 2 second and then screen would go black with backlight. I thought it was the battery so I put the origianal battery and everything was fine. Next day ordered another battery and same thing happened but now even with original battery it only shows the apple logo and then screen would go black but with backlight indicating phone is on. I have changed screen too and know that's not the issue. After seeing the issue then I tried restoring it using itune and I get unknown error 1671. Does anyone know what has happened?

I have repaired iphones 5,5c,5s,6 and 6+ for screen and battery and never came across such case.

really appreciate your inputs.