Replace UEFI boot splash screen/logo (Jetpack 5.0.1 / R35.1)

I have my 16GB Xavier NX production module is mounted in a dev. kit carrier board:

The BSP and sample file system are extracted on a Dell OptiPlex 7050 running Ubuntu 20.04.

By “broke” is mean: initial black screen followed by a brief which screen, and then the normal boot console output. I.e. no UEFI-output or logo, as previously described. Please see the following videos:
With default “uefi_jetson.bin”:

With modified “uefi_jetson.bin”:

The UEFI-boot takes substantially longer when things are not right.

You as for serial console log. Does the UEFI create a log? If so, where can that be found? Or is there any other log that can be useful?