What’s wrong with my car

My Hummer will not start. I have replaced part
after part and even brought my Hummer to
the dealership and still no correction. It won’t
turn over, I replaced the ignition switch and
the black box on the ignition. I replaced the
acceleration pedal, and the shifter lock, and
safety neutral switch. None of these things
have helped my problem. All I can do is get
my directionals to go on, and sometimes the
radio. What is wrong with my car