Jeep Repair: 96 Jeep Cherokee overheated and now wont start, losing coolant, heater control valve

Question
I have a 96 Jeep Cherokee 4.0 liter, 6 cyl.  It was losing coolant rapidly and I found that heater control valve had broken, leaving 2 hoses disconnected.  I replaced part and added coolant.  It seemed to be running fine as I drove it home from auto parts store after repairs. Half way home the overheat light went on.  I pulled over, wasn't leaking coolant, shut off engine to let cool.  Turned back on and light was off so proceeded.  After a short distance light came back on, started to hear a clicking/light knocking sound, lost power then car died as I was pulling over and it was steaming and boiling(still no leaks seen).  Car will not start now.  Battery is ok but when I try to start it I hear only a clicking noise.  There are no leaks that I can see.  Checked oil, no coolant in oil, looks fine. Can't start it to keep troubleshooting.  Next step???

Answer
Your next step would be to remove the accessory drive belt from the water pump. The water pump or another belt driven component may have seized. This could prevent the engine from turning over. If everything rotates freely the you need to try and rotate the engine by using a ratchet and socket on the crankshaft bolt, which I believe is 21mm. If the engine still fails to rotate, remove the spark plugs and try to rotate the engine again. If the engine rotates and antifreeze is expelled from one of the spark plug hole you know that you have blown the head gasket. If the engine still fails to rotate you may have seized the engine.