Dash lights up,won't turn on
 

hey guys,I've been having an issue lately on my i35 .. Seems like after installing my new double din radio yesterday my car doesn't always want to start with the first turn. The lights come on in the dash but I don't hear a cranking sound. Then the car turn on after another attempt. This happens one out of three starts,do you think it's a security issue with the radio or could it be my Camshaft position sensor since I did get the code for it on the scanner. My battery is 3 months old and well the weather in Florida isn't going to affect it. Any help would be appreciated

The usual advice is to recheck the things you touched during installation, it would be hard to guess what you might not put back (if you did install yourself). It is unclear if the lights go out when you move key to START or everything stays the same way as when't it's in ON position. Radio usually wouldn't have such feature, it is usually part of alarm. Camshaft sensor might still be a problem but it wouldn't prevent starter from cranking, so this is not it.

You probably disconnected the battery before installing the radio. Did you reconnect it properly, clean & tight?

Re. the CAMshaft Position Sensor, Max_5gen is right. However, you should be aware that a bad CRANKshaft Sensor can prevent the car from starting because the ECU will shut off fuel when it does not get a signal from the REF crankshaft sensor within a few seconds of you turning the ignition key.