Found the following on a website blog. Does the 737-700 AP have a CWS function?
Re the ANA 737-700 incident. There is not much to go on because only media reports are available at present. So who did what to which is unclear. Maybe when the F/O hit the wrong switch (he got the rudder trim rotary knob) the door didn't click open or whatever the door is supposed to do to unlock. Someone mentioned earlier it takes 29 seconds for the rudder trim to move from centre to full scale left or right.
The ANA incident happened at night. This is significant as we shall see. Assume the F/O held on full rudder trim maybe not for 29 seconds but a significant amount of time. Eventually the autopilot either went into CWS roll as the control wheel turned to maintain the present heading - or the autopilot disconnected altogether causing the aircraft to roll. It maybe the first officer then lost control when he tried to hand fly at high altitude at night in IMC on instruments. Most of his 737 flying would have been on full automatics from shortly after lift- off to shortly before touch-down.
Another possibility is if the CWS roll did remain in place (in other words it had not yet disengaged itself) and the unusual position of the control wheel alerted the F/O to something going wrong. If he then tried to correct to wings level too harshly with CWS roll engaged it may have caused the autopilot to disconnect in the roll mode and pilot confusion with hand flying (lack of instrument flying skills) could eventually lead to an upset.
Or if the F/O inadvertently hit the stab trim switch on his control column at any stage while the AP was engaged in any mode, the AP will disengage in all axis leaving the F/O to hand fly and he probably did not have the ability to do so. It may have been a different story in day VMC but to have a typical F/O steeped to use automatics throughout his career on the 737, then a IMC recovery is going to be a real problem.