Was she moving when she engaged the transfer case into 4 low?
Was she towing 4wd thus the need for low range.
Hello I'm Chris a Ford Certified Transmission/4wd Specialist.
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Ok lets get it out of low first. Drive the vehicle in a straight line for ten feet with the selector in low. Now stop and place the trans in neutral and hold the brakes. Now shift to 4 high. It should clunk in. If not then repeat and have someone tap on the shift motor with a hammer while you shift it again. If it still does not come out then suspect the shift motor.
To diagnose the OD flashing concern you need a scan tool. Auto Zone does this for free.
Here are possible problems.