My iPhone 6s Plus has a new battery (replaced under warranty) but it is not charging and my phone is dead

Start by checking your charging cable and power adaptor, test by substituting different parts. Your iPhone should have been checked and found OK after repair so that tends to make the charger look like prime suspect.

try doing a hard reset first (this won't reset your phone) by pressing the home and power buttons together

if that doesn't work, take it to the Apple Store

Sorry DON'T hard reset your phone

take it to the Apple Store

Hi

Take iPhone back to store.

Cheers

Brian 🇬-1F1E7;