it has been proved if you jack 1 tire of the ground you wont go anywhere with a np203 in the unlock position, if your hubs are unlocked, and the t-case is unlooked all your power is going to the least resistant place, and that is the front axle, since the front hubs are unlocked.
no wheels are turning
try this, lock the front hubs, and put your truck in high/low unlock mode, and the truck should move, if it doesent then it could be something in the case/front axle broke.