Pontiac Repair: 2003 Pontiac Grand Prix SE issues., pontiac grand prix, noid light

Question
I bought my son this car about a month ago (3.1L V6). It ran fine for about 2 weeks, then out of the blue he called and said it wouldn't start for him at work.  He checked the battery to be sure it had good connections.  After about 15 mins, the car finally started (after numerous tries).  He got about 5 miles down the road and the car started running hot.  He pulled over and called a tow truck to bring it home (so he wouldn't cause any damage to the engine).  We have gotten the codes and replaced everything that it said was needed.  Thermostat and O2 sensor to be exact.  The car still will not crank.  It turns over and acts like it wants to crank, but it wont.   There is no water in the oil, radiator is full of water and coolant also.  Plugs are getting fire, engine is getting gas and there are no visible leaks of oil or water under the car.  Any ideas what we should try next in order to get this thing cranked so we can find out if the overheating issue is fixed?  Thank you so much for your time.

Answer
Hi Michelle:

does this have a security lamp on the dash flashing? If so there may be an issue with the pass key secuity system in the car. the 2 issues you have here I don't think are relayed unless the engine was over heated severly. If that were the case the engine could be lacking compression and if that is the cae that is not GOOD! start with the basics. it needs spark compression and fuel Just because it has fuel pressure doesn't mean the injectors are working a NOID light plugged into one of the injetor plugs and cranking the engine should produce a flashing light if not then the security systemn could be inhibiting injector operation. those are a few things to start looking at. good luck :)