Just an FYI.
There was a post of the N54Tech forum i read, where someone while loading a flash tune via MHD.Midway through the write process it stopped.
The guy could not get the car started. Tried several times to complete the flash but it did not work.
Eventually after getting some assistance from another follow forum member, he was able to load the flash and start the car.
The reason why it failed during the write process was because his phone was not in airplane mode. There was an interruption to his phone during the write process which messed up everything.
So if you using MHD turn your phone onto Airplane mode, until you complete the flash.