Hi,
Wanted to share a how to fix/repair/removal for my 07 Monte Carlo-Shift Interlock Solenoid/switch, shifter, center console, for anyone having the same/similar problem.

This problem was an intermittent problem which got worse, where the ignition key would not turn all the way off to allow the key to be removed. This would also result in the car battery being drained over night if the key was left in out of desperation.

The problem part was discovered to be the Shift Interlock Solenoid/Switch (Dorman 924-978?) sticking.
But I didn't have to buy a new one.
I found mine, the white button was gummed up with spilled soda/coffee, which kept the white button from popping out fully when the car was in park.
In hind sight, I probably could have fixed the sticking with electric contact cleaner spray or just rubbing alcohol dripped over the white button while pushed in and out. But I couldn't see that for sure till I took the interlock out and opened it up to inspect the inside.
So you can short cut my work and get same results.

This Interlock Solenoid & Switch does several safety things. It's metal round solenoid energizes (also has a manual button release) to allow the shifter to come out of park. The solenoid is energized when you place your foot on the brake.
The Interlock white protruding switch, when extended, electrically tells the ignition that the shifter is in park, so that you can remove the ignition key fully.

We had already dealt with this problem and fixed it a few years ago.
But at that time, the problem was that the connector wire harness thin internal wires had metal fatigued from the shifter movement they must flex with and so broken inside. Splicing in superior replacement connector PT3923 fixed the problem till now.

To get to the Interlock box, basically:
Pull up-off the 2 cups drink holder which just snaps in place in its 4 corners. Be careful not to break any plastic, as they may be stubborn or gummed up (when reattaching, place a piece or two of scotch tape over any/all metal male retainers/clips which will allow much easier removal in the future).
Pull up-off from the rear, the top plastic panel of ash tray lighter whole section panel.
The rear has 2 pull up clips, but the front has 2 locating prongs you slide the panel rearward to remove last.
Use Phillips driver to remove now 2 visible screws at the sides of the shifter.
Use Phillips driver to remove center console arm rest cover/door.
Use 3/8" socket to remove 2 large screws at bottom inside center console storage well.
Disconnect exposed plugs for rear and front power/cigarette lighter.
With park brake applied, move shifter to neutral and lift the entire center console shroud off and away.
Interlock box is now exposed. See how when in the shifter is in park, the short white button is allowed to come out fully.
If the button is sticking, apply rubbing alcohol around it while moving the button in and out.
ALSO spray some WD40 or similar light oil into the solenoid button's shaft to improve its easy operation, especially in the winter time.

If you need to remove the interlock box. unplug it and:
Move shifter forward and backwards as you flex manipulate the cover/slider up over its retainers.
Either swing the cover/slider side ways out of the way or remove it by: Use a Philips driver to remove forward screw below shifter ****. Remove shifter ****.
Use a small torx driver to insert from the top down to remove both long retaining screws for interlock box. You'll have to move the shifter as needed for the best angle. Park may be best.
Once removed, you can remove the 2 short torx screws to open the box up. It just has a center seam.
Inside there is circuitry which knows when the white button is in or out, Also there's a micro switch which is pressed if both the white button and the solenoid are pushed in at the same time.
I didn't look at a wiring diagram. I can say that the ignition key will not come out if the wire harness is unplugged from the box or if the button is stuck in(like it's not in park).
Use a wet rag to clean out any soda/coffee residue.
They spray with some silicone spray and/or apply some vaseline, to the moving parts.
Also, apply some vaseline on the shifter's frame positions selector which a metal rod moves on.

If there is much spilled coffee/soda under your entire shifter frame, you can remove the whole thing for cleaning etc. by also:
Use a flat screw driver to pull up the flat metal U shaped retainer which is where the shift cable enters the front of the shifter frame.
Use 2 flat screw drivers to pry/pop off the shifter cable end off of the retaining ball.
Pull forward out the shifter cable from the shifter frame.
Use a 1/2" deep socket to remove the 4 floor shifter frame retaining nuts.
With the shifter frame removed and upside down, lightly silicone/wd40 spray any shifter moving parts pivot points hinge.

*When reassembling, stuff some strategically placed and folded paper napkins under and inside the floor bottom of the shifter to catch/contain any future liquid spills...

ALSO take a short piece of absorbent foam/similar and glue/tape it around the shifter rod, just above the Interlock box, to act as a drip catch/barrier to liquids dripping all the way down again onto to the Interlock box's white button causing the problem again.

Take care