if they are anything like the granada seats the motors will turn and they operate directly onto the threaded metal bar to move up and down, it is either the bar that's come off at one end or the motor acuating thingy has broken

the sure way to test if to press the button and see if it stops, if it does then it's the arm come away from the mounting, if it doesn't then the motor isn't acting on anything

from the sounds of it, the motor has come away from the moving bits and needs reattaching