My 09 Sierra 4.3 won't crank. I turn the key and nothing. I checked online and youtube said try finding and swapping relays. Didn't change. Another said try disconnecting the BCM and grease it and reconnect it and that didn't work. There is no click, the truck doesn't even try to turn over. Everything lights up like normal on the dash. The radio works fine. I even tried jumpstarting it and still nothing. This has never happened before. I don't know what else to try except take it to a shop. Things were so much easier before all this computer crap. Probably the simplest thing but I don't have a clue. Any incite would be much appreciated. Thanks in advance.