I have a 2011 Infiniti G37x 4D and I recently got into a frontend accident. I hit the passenger side of the car and it seemed purely cosmetic, I left my car to sit in the cold for a week afterwards without driving it and I tried starting it and it struggled, but started, the battery light and the e-brake light illuminated on the dash as well. I drove it down the garage and it went limp on me, came back to life with a quick jump and I was able to drive it for a week. There was seemingly no mechanical damage, suspension was fine, car ran and drove like new. I got a new battery just in case and the dash lights went away. A snowstorm ran through the city and after it was over, I tried to start my car but it would not start. I tried jumping it and it would start but my battery light came on and the e-brake light, same symptoms as right after the crash. The car would die right after disconnecting the jumper cables from the donor vehicle, the car would try turning over but just did not have enough power to start. This led me to believe it was my alternator. I took everything apart and came to find out my alternator was pushed against the engine block and has a gash all along its center. I replaced the alternator, made sure my battery was healthy and charged, and my car still will not start, same symptoms as before changing the parts, it will try turning but it will not be able to, which makes me think it is not a starter. I am wondering if I need to put every sensor back and fill the liquids in order to start because I have the radiator pulled and its out of coolant due to replacing the alternator. I am wondering what I am missing? Maybe it is parasitic drain? Blown battery-alternator fuse? Starter? Faulty Alternator (I got it off of LKQ)?

 

Sorry to say, you've got a lot more damage out of your shunt than you think. How many miles on it? If you have collision insurance, a more complete diagnostic might have been done. The electronics on the G are more complex than you think, but that crash really damaged the electronics. With all the damage I wonder if some grounds were disconnected?

 

Pictures of the damages? If the impact was so severe that the "alternator was pushed against the block and was (physically damaged)" then you potentially have more issues than you might be aware.

To me, the no start/ dead battery issue presents as a symptom of some parasitic drain. Depending on what sensors/ electrics were damaged the car might not be "going to sleep" as it traditionally does ≈10min. after shutting the car off. Again, without some type of physical reference it is hard for us to gauge.