Hi Joao
I tried to reproduce this here.
With my EDT 7" display I do get (the Toradex) splash screen out of the box but with a EDT 5.7" I don’t get any sensible output on the display. Both are connected to the Unified Display Connector.
Surprisingly the 5.7" display looks at the RESET_MOCI_EDT# signal while the 7" display does not.
Could you try to test if that is the issue you now have by e.g. releasing RESET_MOCI# with the following command in the U-Boot console:
gpio clear 28
Max