I'm having the exact same problem.
One day was fine, towing a Uhaual trailer to help a friend move.
2 days later (didn't drive it the day between), turn ignition and it just goes CLICK.
Not the repitition of a dead battery, just a single CICK.
It seems the fuel pump isn't priming, either. I don't hear it and when I press the relief valve on the fuel line, only a tiny little bit dribbles out. That's with the ignition on.
All fuses check out. All lights and other electricals work fine (lights & radio and windows and such).
Battery fine.
All the grounds and wires that I can find look ok.
I even jumped the solenoid, and hear the starter motor do a single CLICK, then nothing.
I moved the shifter around, and tried starting in neutral, but get same thing.
Help?