Just bought a 2004 350z convertible ran fine for a month now squeals in engine compartment , probably tensioner but now can't get car to crank, new battery, will check all fuses in the morning?
Lost ??????

Welcome to NICO!
Squeals are not normal, if it's just a belt squeal it's likely unrelated to your no start issue.
It could be as simple as the starter, or a battery cable but there are more possibilities depending on if it's a manual or automatic. Being convertible I'll assume auto. Neutral safety switch could be at fault, if it's a manual the clutch safety switch or even the rubber grommet it contacts could be at fault. Could also be a security issue, what does the security light do? How about all your other electronics? Everything else working?

Yes it's automatic, all lights radio good, security light blinks when key out and off with key in, checked all fuses I could find (3 sets)
How would I check the neutral switch and the starter ?
Right before it quit working the starter seemed a little hesitant so afterwards I got a new battery - not cheap I might add.
Thanks for the reply hope to get this narrowed down soon

If it seemed hesitant before and a new battery didn't improve things it's most likely the cable or the starter, you can take the starter out and to most parts stores where they will test it for free. Before pulling it make sure the power and ground connections are good at both the battery and starter.

Thanks for the advice
Fi you know if I power check the starter cable (to see if it's getting power)
Would be 3 - one to battery, negative, and starter switch? Then would I have to have ignition turned to see power going to it?
All of this done from under car driver side ?

Just make sure the cables at the battery are terminated securely and no loose, make sure the other end of the cables is also terminated securely and not loose. the starter does need to be removed from the bottom.

Thanks for the good advice got a starter for 54.00 and fired right up, now to figure what belt or tensioner is squealing