Sounds like you probably have a bad clutch. Did you try directly jumping a ground and hot right to the clutch plug? If you tried and didn't hear a "click" then the clutch is probably bad.Yes, I had the green connector apart when checking that the switch was sending power to engage the diff.
Switch is sending power. Still no 4wd.
If you want to test further before you buy a clutch, you should clear all your codes, remove the Hess bypass and start over. Keep in mind that i4WD will NOT engage with the motor stopped, it must be running. If you try to engage it with just the key on, the 4WD indicator in the dash will just rapidly switch between 2WD and 4WD. It will also do that if there is a problem with the system.
With all codes cleared, then you can start from scratch. You should get the stock i4WD working first, then re-attach the Hess stuff. Disconnecting the battery will NOT clear the codes. You must use this procedure. You can use some small solid core wire or small paper clip for the jumper and jump Brown/Red to Green...