You need to get into Nindy and reload the code.

How this is done, depends on the model of the shelf controller:
1) if it has a tiny rotary switch accessible from the far left on
   the back panel, then set it to 0, power cycle the TNT, connect
   a terminal to the console port at 9600,8,n,1 and you are ready
   to go.

2) if it doesn't have the switch, then, connect a terminal to the
   console port at 9600,8,n,1, power cycle the TNT and within
   10 seconds of the first prompt you see type "Ascend" (it is
   case sensitive). That should get you into Nindy.