Replaced screen issue MBP 2015

I got MacBook Pro Early 2015.

Display unit replaced due to coating issue, 2 years ago. I noticed that I do not get backlight whenever I boot the computer. I can not see the Apple logo unless I shine a light through the back of the display.

However the backlight works flawlessly when I'm logged in and never flickers or anything. I have already tried to reset the SMC and NVRAM but that does not seem to fix the issue.

I read about this issue, and seems like they replaced MBP 2015 with late-2013/mid-2014 retina display.

How can I be sure about it?

Printed report shows only "Display replacement" there's no part number or anything else. Also this done by an authorised reseller. So based on Apple's records, there's no info about replacement parts.

Also I visited Apple Store, they just offered Mainboard and Display replacement for a almost new macbook price :)

I'm open for new ideas.