I said transmission not the transfer case, sorry I miss typed, but I’m thinking the problem could be one of a two things. First the linkage may be binding as you changed it while the case was out. I would go back through the install and make sure all looks good. Second, gears inside the transfer case may not be lining up with things inside the case. You may want to try turning the guts to the case either by rolling the jeep forward and backwards if the rear drive line is in place but if not try turning the rear yoke by hand. It may be necessary to start the jeep and gently try releasing the case