Whether or not the radio goes off will help pinpoint the problem, as the radio should go off while cranking. If it does not go off the problem is in the ignition switch contact that commands the BCM to operate the starter. If the radio does go off the command is being sent, but either the starter relay in the underhood fuse block or the starter itself are sticking.
I would turn the ignition on and make sure the radio is on, then turn the key to crank and check to see if it goes off while the key is in that position.
Sky NA 2007 Midnight Blue
Sky RL 2008 Carbon Flash - Naked