My son has a 2004 G35 Coupe. He had a little incident in the driveway a couple of weeks ago, and cracked the tail light. I bought an ebay replacement, reinstalled it, and light works fine. Unfortunately, on startup I have an issue with flashing lights/instruments (radio lights/compass/temp,etc.). They flash @ 30 times, then pause, then flash 30 more, then another pause, then 30 more. Same sequence every time. Car seems to be running fine. I searched and couldn't find anyone with similar issues. Any ideas?

 

Did the problem exist before replacing the tail light? If no, try connecting the old light assembly and see what happens. Does the car have an after market alarm system?
Try locking and unlocking the drivers and passenger doors using the key to actuate the lock cylinder mechanism.