1998 Yukon Transfer case Problem Need Help

I just replaced my torque converter and my transfer case front seal. I was testing it and then it got stuck into 4wd low. I took it to the chevy dealer and had them run a test on the transfer case (233.00 dollors) and they told me I needed a transfer case motor. I replaced it and then the transfer case was stuck in neutral. I took it to chevy to get it programed and now it is stuck back in 4wd low and at the chevy place. They have no clue what i wrong. Need help please.. Thanks (Sorry so long)