a friend of mine has a 2007.5 6.7 cummins. deletes done and around 140k miles. when he turns the key on it doesn't do anything. nothing turns on and truck wont start. makes a little odd noise when the key is turned off but other then that it acts like the batteries are out of it. I just am wondering where to start. when it first happened he was a block from the dealership so dropped it off there and they just gave it back to him with the answer "we don't know whats wrong with it" any suggestions will help. thanks

 

check all fuses, make sure nothing is unhooked, batteries, wires...