So I have 2008 g35 sedan. For the past few months my car has only been idled from time to time due to plate issues and me not being able to drive it. About a month ago when I turned off my car I'm not able to use the key to lock the doors. And I have to use a JNC660 booster pack to start the car each time.

 

After my car is started even if I drive it around, once I turn it off the battery is dead,also when the car gets turned on and I turn on the interior lights, they flicker.

 

Simple stuff first.
Test your battery.
Test your alternator.
Both are cheap and easy to replace.

 

You probably have a defective battery. Ive seen this issue before.

Get a new battery first. I think that should solve your problems.