I have a new STM32F469-DISCO board with marking DK32F469I$AU1 which is supposedly corresponding to a mainboard revision MB1189-F469NIH6-B08, according to STs UM1932 manual:

The Board has a a new touch panel and "severl part references updated":

When I try to flashing any of the display examples, the display doesn't show anything.

There is a limited datasheet for the FRD400B25025 display in this thread, but for now I didn't find helpful information in there to get the display to work.

The people in this thread seem to have a similar issue and got the ST TouchGFX Desginer 4.21 as response from ST... not sure how easy it is to extract values from that software. However, the thread says, the new driver might be a NT35510 instead of the old otm8009a.

For the NT35510, there is a pretty long datasheet available...
AND... there is an ST Driver for it on github

I also found CubeMX generated Code that is supposedly running this driver.
The USE_STM32469I_DISCO_REVC seems to select the version B08 on the boards marked DK32F469I$AU1.