Fwd locks in unexpectedly

Your onboard computer is letting you know that it has detected an electrical problem in your four wheel drive circuits that requires attention. It could be a loose wire, or corroded connections or a switch gone bad. I'd check the connections and wiring first.

It can be fixed without removing the engine. What car is it? cause it depends if its fwd or rwd, the fwd usually need the exhaust removed before removing the oil pan

try it in dirt yet (gravel, sand, grass dirt)
since you didnt post transfer case type can't answer
if you use , part time 4wd on dry pavement this will happen as
will 4low or lock. read the operators guide, one more time.

its a new car get it serviced, or drive in dirt, and turn off 4wd
see if it stays off. if you use the car wrong, the dealer will just stare at you, in a very not so funny way.

new cars come with options, or by sub model, (same really)
some have Automatic Full-Time Four-Wheel Drive
which one?
The Compass also features two electronically controlled four-wheel drive systems. Freedom Drive I and Freedom Drive II, Freedom Drive I is a full-time four-wheel drive system with locking capabilities

if some one used LOCK
you need to unluck in dirt. drive to side of road with gravel
or any loose surface and get bad to normal.
read opeators guide 1 more time.....

With out actually seeing the vehicle the possible issue could be either a bad 4x4 selector switch or the shift motor on the front differential

It sound like you need an ignition switch. One of the pieces inside is probably broken, not allowing the key to turn back. The gear shift thing may be related since it won't lock the ignition.
Hope this helps. Good luck!

POSSIBLE IGNITION MODULE,

Your car has a security function, which assures that the vehicle is locked when left without driver for a while. Same happens if you unlock the doors with the remote and don't open any doors for a few minutes. The doors will lock themselves.

The light blink's to warn its not properly out of 4WD. When the light blink's it is recomended you reverce a few meter's to allow the front axle to disengage.

check the fluid

Most electrical problem occur without warning unless there is a built in trouble sensor. Mechanical problems on the other hand do give you some warning most of the time.