I see a couple posts below with the same issue but I'm not having the same resolution.
I have a 2012 Cummins 6.7 the truck was returned to me a week ago due to ecm failure.
The truck was driving perfectly fine(except for egr warnings).
Decided it was time to put the tune back on it.
I purchased my VIN license direct from efilive and had it within minutes.
Upon following the proper steps(2010-2012 6.7CMD Mercenary Instructions), I unlocked the ecm and began flashing the tune file to the truck.
When the flash had completed and I turned the truck off, when I turned the key back to on, the truck was completely locked!
What could have gone wrong? When the truck locked up like this last time(2 months ago) that encited the new ecm.
Please help.
I'm also putting an inquiry into efi customer service, as I believe they have some explaining to do.

Thanks