No crank no start

Hey MPNANTO,
I'm not exactly sure what the computer said Because my mechanic was doing the test and just telling me I know he said that there was no communication with the pcm and the faults kept saying powertrain control module and he tried to reset it and it just kept popping up. The check engine light does come on when I put the key in but all the lights come on and when I turn the key all the way everything shuts off and nothing happens at all. When I had the keys reprogrammed to the new pcm the computer was communicating with the new pcm just fine and everything looked good there was no faults at all and the same thing happened when you turn the key all the lights come on but when you turn the key all the way everything shuts off and nothing happens

How would I get the code numbers? I'm lost I have no idea what else it could be. Someone told me it could be the fuse box but I don't think it's that. When I turn the key I can hear a click by the wires behind the glove box by the fuse box but I don't know I know a little bit about working on cars but not much about electrical.