Bench flashing is sometimes the only way to get a map to load. Some cars shut off power after a few minutes, so on some models you need the ignition key in the on position without running the engine, on others it doesn't matter.
Is the map correctly setup with all the right checksums, I've known errors in the map can cause it to stop uploading.
Does this mean the car is dead, or you are stuck on the factory map?
Has anyone else remapped it in the past? Sometimes a map is "locked" by tuners, to "protect their copyright" and "prevent accidental reflashing when going in for a service".
My experience is mainly Audi/Vag group so I can't comment too much about the setup on the Silverado.
Also I'm sorry for my slow reply, it's been a bit frantic here, but I'm hoping to get back in the forum again now.