Iphone 6 got switched off, I tried connecting to itunes for software update but giving me 4013 error iphone is disconnecting from laptop after extracting software

my iphone6 is only 6 months old phone got switched off automatically. I switched on then it got oned and placed in charge once again phone got switched off..

After seeing in google and support ..I connected to itunes for software update, software downloaded after extracting software step phone getting disconnected.

serial number:N/A. then network symbol in phone is still with apple logo.getting 4013 error.