Pontiac Repair: 2008 G6 4L V6 Intermittent No Start

Question
Have a 2008 Pontiac G6 that wouldn't start about a week ago.  Morning start, lights came on - but when turned key to start there was nothing….no clicking, no noise at all. Have extended warranty so called GM Roadside who confirmed start problem and said it wasn't battery.  Had vehicle towed and next day dealer said they changed battery and car worked again.  Car did work for 3 days and then this morning same thing - lights on and no start - no indication of attempt to start.  Car was towed again and at the dealership the car started fine.  Sounds to me like a poor connection somewhere that the "jostling" of the tows.  Dealer said can't replicate and no codes……I left car for a few days hoping it happens again.  I can't trust this car right now and I don't want to be somewhere bad or extremely inconvenient when this happens again.  What do yo think this is?  Corrosion somewhere, cab els, Ignition?

Answer
HI Patrick.

well first off if it's been to a GM dealer that is a good move Vs independent repair shop. question is this what codes have set in this car when it will not start, there should be a smoking gun some where one or of the modules in the car should have set codes to point in one direction or the other as to what is going on. question when it would not crank or start did the odometer on the dash read "error" all of the computer modules on this car are connected in a network and if one of the modules goes down it can effect the rest of them and cause a no crank issue. one common issue these cars have for that year doesn't matter what engine is that they had bad negative battery cables the cable would actually break off at the engine end and cause no crank and no start issues.  obviously with out seeing it and with out knowing what if any codes are stored in this I can't really give you a direct answer as to what the issue is. good luck :-)