But, wait! If the battery was really dead, you HAVE to reinitialize the Gryphon with the "ignition ON, then plug the unit into the OBD port" procedure.
Please try that before you go getting another unit!
1. Unplug the Gryphon.
2. Turn the ignition key ON but do not start the truck.
3. Plug the Gryphon back in.
If it starts and shows your HEX code, you're in business.
AND, losing a battery charge, or disconnecting the battery does NOT remove your custom tune. Only the Gryphon can do that (or a dealer reflash).
Edit: I just re-read your post about charging, and see you did "unplug, replug". I'm not seeing that you had the ignition ON. If you did, and it still does not work, then the unit IS probably toast.
- Jack