I try to not get in the way of support anymore since I am usually not in the loop of all that is going on.
But assuming no reply has been sent yet, I would try to do the debugging steps again. There was another topic like this one some months ago where I posted instructions.
For more advanced usage, you can try SSH=1 ./boot-fel-restore.sh instead of running the script directly (note that this only works with the “debug” version from the link on that other topic).
The SSH mode is what we use to debug into the unit and see if anything is wrong, run tests etc.