2007 Chevy Trailblazer stuck in 4 Low?

[Two Pretty in Pink]

My husband was testing out the 4x4 option on our 2007 Chevy Trailblazer and for some reason we can't get it out of 4? low. We've already experienced the "gas cap" issue that is apparently very common with this make and model - is there some little trick we need to know about or what should we be checking on?

[boogie_4wheel]

transmission in neutral, brake pedal pressed. that should get it out of 4L unless the actuator on the t-case is damaged or has become unplugged.