Look in the owner's manual, there should be a manual release procedure. Usually there is a small port in the console near the shifter. A pin or screw driver is inserted to release the shifter.
Are you getting any message on the HU display about "shift to park" or "depress brake to start"? Or in my case on a '13, there is a goofy little light on the dash, a circle with a foot on it, that stays illuminated until you push the brake while in park. First thing that comes to mind is either a shift position sensor, a brake pedal position sensor or the shift release micro switch as described in this video.