This is going to sound a bit crazy, but you said the bolt on the ground strap was loose, Was there a burn mark on the eyelet or the bolt by chance?
I have seen where the main ground wire from the battery isn't making a good contact at the block and that little grounding strap gets burnt and sometimes even melted when the engine is trying to crank over. When everything looses the ground it will reak havoc on all the electrical systems. Try disconnecting the battery, touching the 2 cables together for a minute or so and then try restarting the truck, it might have just locked up the ECM and the instrument cluster.
So I'm just now getting back to work on it since I've got my car to drive, but are you saying that if it is burnt, a new ground wire should fix it, or do you think it actually fried the computer?
I gotta say, when i first saw the thread title my first thought was you were having problems with a woman.....
I could see that one coming next.