Hi.... I believe the app only works for Pre-Facelift.
I've used a coloured sweet cellophane wrapper to make mine red (ish).
If you are talking about the mode button then there is coding for both Pre and Post facelift models.
Mode button always in Red
* Applicable up to MY16 *
1 - Module 09 - Electronic control unit - Code (31347)
2 - Long Coding(Bytes Mode)
3 - Byte 15 - (Activate Bit 7)
In this mode it will always be illuminated in red.
*Apllicable from MY17*
1 - Select Control Unit 09
2 - Select Adaptation
3 - Select Button in center console
4 - Select Zusatzcodierung Farhrprofiktaster hat keine LED
5 - Change to Led not installed