Yeah probably different countries have different button configurations, maybe a first run from the IX, or simply a AX colour change Kit was used, hardly matters tho, as you do you have IX platform.
No I don’t believe changing the colour would void the warranty, so it seems they did the colour change for you this would confirm the difference in buttons, and yes you can find warranty with the serial number,with the older models there was a way to work the date of manufacture out, but I believe you can just pop the button off and read what it says there.