Hi there! My name is XXXXX XXXXX I think I can help you resolve your problem!
I don't know a whole bunch about Cat but if we stick to the basics we may be able to resolve the issue.
If it is not trying to fire at all on any cylinder, then it sounds like you may not have power to the ecm to energize the injectors to spray fuel into cylinders . Does your engine lamp come on when you first turn the ignition on (should only come on for a second as a bulb test , then go out)? This should indicate that the ecm is powering up or not. Most trucks have smaller wires leaving the batteries that feed directly to the ecm . These wires will likely have an inline fuse right in the battery box. I would start by checking the inline fuse holder for a blown or melted fuse due to bad connections there. If your ecm is not powering up , you could crank forever and nothing will ever happen because ecm is not powered up to fire injector coils.
I would follow those wires right up to ecm to make sure they are secure and not rubbed out anywhere . Look for corroded or loose connections . Good luck!