OK, some definitions first :
crank = engine turns over but does not start
no crank = turn key, engine does not turn over
start = cranks and engine catches

so now :
no crank = RCM failure or totally dead battery or battery ground problem or burnt out starter or bad pulse module
crank = no ignition or fuel ( out of gas, bad fuel pump, clogged filter or bad CPS ( crankshaft position sensor )
start = if engine runs only 2 seconds or so, then you try again with same 2 seconds, then on third try no crank, then you have a bad SKREEM

Hope this helps