I have a 2004 g35 coupe... I drove it to work this morning everything worked fine.... This afternoon I got in to start it up and the engine will turn over but it doesnt sound like it is firing... I checked all my fuses and relays and disconnected the neg bat cable to reset it but still nothing...

SOURCE: overheating

My 04 G35 is overheating. I have read forums on the issue. Everything from a gasket on the rad cap, to bleeding the system, flushing the system, to a new thermostat.
I took it to the dealer and they said the cap is ok, but there is a very small drip that they can not find. They refilled it and there was no problem.
Today, a week later, the temp gauge went almost to H and when I got home I looked under the hood and the antifreeze resevoir was empty!! I had no heat either, but this makes sense if their was no anti freeze.

SOURCE: How to remove jammed cd infiniti g35 coupe

This is a stereo we see in shop for repair on a regular basis, see www.carstereohelp.com for repair. However, I have one suggestion before thinking of repair. Disconnect one of the main car battery terminals for several minutes. This is much easier then removing and reinstalling the stereo in this car. This may act as a reset and bring the changer back. Otherwise, repair is needed.

SOURCE: engine turns over fine , car will not start.

well the first part of your question i was all ready to tell you to put a new fuel pump in, now not so sure, there is a relay for fuel pump, can you hear pump cycle and relay click? relay under hood you will have to listen close they don't run long maybe a couple secounds, if you don't relay bad. if you do pump could be bad, do fuel pressure test pump could be weak. don't think sunroof and turn signals are related, but stranger things have happend.

SOURCE: how to remove factory 05 g35 coupe 6sp

The stock radio system is three pieces. You have the outer display, behind that is the audio circuit board, and behind that is the actual radio, which looks like a plain square silver box. The shifter knob should have a piece on the bottom that snaps in. That piece slides down and there is a gold cotter pin that holds the shifter knob on. Remove the cotter pin with a small screwdriver and the knob will lift off. In order to remove the radio you have to remove the shifter knob, the console trim in front of the arm rest, and the radio trim should just unsnap and come out. If you are wanting to install a aftermarket radio, I would consult with a car audio store as to what is involved with this installation, because you are likely to get in over your head. 

SOURCE: change belts on g35

Here is a DIY (Do It Yourself)

http://forums.nicoclub.com/zerothread/342311

Loosen the bottom 2 bolts that loosen the belts, take off both belts, put new belts on, tighten the belts to specifications. Done.