Link doesn't work for me and there are lots of "Redmi Note 4 battery drain fix" videos on YouTube so I don't know which one you're referring to.
For what it's worth I'm using a Redmi Note (3) and a friend is also using one (Note 5) on 48 and neither of us experiences unusual battery drain.
Please clarify which video you're referring to and what the alleged fix involves.
What service centre number are you talking about?
Hope this helps.
If you're experiencing battery drain then it's most likely some app that's at fault.
The battery monitor in your settings should clarify if any app is using a lot of power.
Hope this helps.
Any update @alandunne?