After months of toing and froing with Microsoft Support on this issue and after their level 1 & level 2 support doing exactly the same diagnosis on my device, they said I have two options.
- Escalating the issue to level 3 support.
- Providing me a replacement device.
Replacement devices are refurbished devices but as the support consultant claimed it will come with 1 year warranty (my device warranty expires in few weeks), I opted for that option and I received the replacement today. I had to send my device to them before. However my Microsoft Account displays warranty until 16th July which is only 2 weeks extra warranty, so now I have to go back to them on it.
As for the battery performance, I have no idea yet. Will keep you posted.