OK, this is really beginning to sound to me like a cable problem, although in your first post, did you say you actually tried it with a new cable? If so, it's not that.
Another possibility is something got corrupted in the firmware, which Bill can fix. Having your truck at Level 2 complicates things, but Bill can work around it. I have to think your screen driver's fine if it lights up when connected to the PC.
You'll need to submit a trouble ticket:
Support Login That's the best way I know of to get things working now.
- Jack