From Associated Press:

TOKYO — A Japanese airline says one of its jets nose-dived and rolled almost upside down earlier this month because the co-pilot hit the wrong controls while trying to open the cockpit door so the captain could return from a restroom break.
Two flight attendants were slightly hurt and four passengers got airsick when the All Nippon Airways Boeing 737-700 with 117 people aboard descended sharply, veered off course and went belly up over the Pacific on its way from southern Japan to Tokyo on Sept 6.
ANA said Thursday that the co-pilot is believed to have mistakenly hit the rudder controls instead of the door lock to allow the pilot back in the cockpit. It said the crew managed to stabilize the plane after the co-pilot's error and land it safely.
Japan's Transport Safety Board is investigating.

I didn't know that the rudder pedals were right next to the door locks on Boeings.

Rudder trim, perhaps? Isn't there some kind of alternate rudder or aileron trim-switch on the center pedestal on Boeings? (Been a while for me)

But the door knob still isn't that close to the center pedestal.

Who said anything about a doorknob?
Lots of a/c have a door unlock switch on the overhead panel.

its a round trim knob about 6 inches from a much smaller blade style door unclock switch. Its conceivable that this could happen but you would have to have your head pretty far up your

My 737 cockpit experience is limited to a few jump-seats but I thought the cockpit door release is a square button to the right of the electric rudder trim knob. Do you suppose he held the rudder trim until the autopilot disconnected, all the while wondering why the door wouldn't open? Good lord.......

Wrong Button Sends ANA Jet Nearly Upside Down - Japan Real Time - WSJ

In a chilling reminder of how a simple human error can override the highest of high technology, an investigation has shown that All Nippon Airways Co. narrowly escaped a catastrophe earlier this month when its plane almost flipped over after a co-pilot hit the wrong button while trying to open the cockpit door for the plane’s captain, returning from the restroom.
The revelation came at an awkward time for the Japanese carrier, just hours after the first of the new-generation Boeing Co. 787 Dreamliner jets on which it has built its future strategy finally landed in Tokyo on Wednesday, more than three years behind schedule.
The celebratory mood was quickly over as Shin Nagase, a senior executive vice president at ANA, apologized and bowed deeply in front of TV cameras at a news conference to apologize for the trouble caused by the incident, which took place Sept. 6.
According to the Japan Transport Safety Board, two flight attendants were slightly hurt when the Boeing 737-700, with 117 people aboard, tipped more than 130 degrees to the left at one point and dived about 1,900 meters in 30 seconds during a flight from Naha on the southern island of Okinawa to Tokyo. Two flight attendants were slightly injured and six passengers became airsick or reported neck pains. (Watch a video of the mishap compiled via computer images on the transportation ministry’s site here).
ANA said a 38-year-old co-pilot likely hit the rudder trim controls by mistake instead of pushing the door unlock button to let the captain in after he stepped out of the cockpit to go to the restroom.
Computer graphic images compiled by the safety board showed the plane turning almost upside down, but many passengers on board apparently did not realize the gravity of the situation, since it was already dark outside when the incident occurred at around 10:50 pm.
Investigators said the co-pilot was quite experienced, with more than 35,000 total hours of flight time. Nonetheless, according to investigators, the slip-up cause a roll and descent so violent that the jet exceeded certain maximum allowable speeds and also was subjected to stresses beyond its acceleration limits.
The safety board will continue the investigation, while a company spokeswoman said ANA will take preventative measures to make sure that pilots do a double-check on where the controls are located as they leave and return to the cockpit. The company said it will also try to improve its reporting lines, admitting that officials were not aware of the incident until the following day.
IF true, to have 35,000 hours, he would have logged 4.8 hours a day, EVERYDAY, since the age of 18. What's the word I'm looking for.....oh yeah...BULLSH$T. Sounds like he lived by the motto "Log what you need..fly what you want" or that is one major typo.

.. just a long commute.