S6 - Full battery draining in less than 1 hour after battery replacement

[Android Central Question]

Hi, I have an s6 i recently had a technician replace my battery as my phone stopped powering on suddenly. My phone worked fine for 1 week and still charges however after full charging my phone last night a full battery drains from 100% to 0 with only light/moderate use such as internet browsing in less than an hour. I have gone through basic trouble shooting/optimized battey and closed all apps ect but nothing seems to work. The battery drains as normal when not in use but only when nothing is running in the background.

i dont recall any recent updates, the phone has been repaired for a screen fix and charge port issue while under warranty however had run smoothly for several months before this issue.Any advice would be greatly appreciated.