Mazda 3 won't start
 

I have a 2007 mazda3 that won't turn on... When I put the key in the ignition it clicks once then nothing.

Battery and alternator are fine and I just put a brand new starter in thinking it would solve the problem.

I'm at a loss for what it could be

Either there is bad connection in the battery cables or your car's engine may have an internal mechanical problem. Check your engine oil.