Nothing like hitting the wrong button! But here's what can happen even if the right button is used. This happened just last week, as reported by my neice:
"Dad's Air Canada flight to Toronto was supposed to leave the L.A. airport at 11:40 am. He arrived at the airport in plenty of time, and so, knowing his family well, picked up four coveted, fresh loaves of authentic sourdough bread to bring home. With loaves in hand, he and the other passengers boarded the plane on time. However, with the doors closed and seat belts securely fastened, a strange squawking noise came across the P.A. system. Passengers exchanged curious glances, then the noise was heard again.
It turns out that squawk was the pilot's attempt to greet the passengers. However, the P.A. system seemed to have lost the ability to properly transmit his voice. With the passengers still on board, mechanics were brought in to try and revive the tired system. They consulted with experts in Montreal, but still, unintelligible squawks were the only sounds that could be heard.
After awhile, passengers were told that power to the plane would be shut off for six minutes, in hopes that the system would reboot and the problem would magically disappear. Of course, turning off power to the plane meant turning off the air conditioning as well. Not a big deal if they'd been sitting on the tarmac in Toronto, but this was a fully booked plane sitting on a stretch of black asphalt in L.A. with the noon-hour California sunshine beaming down in full force.
After six sweaty, stuffy, hellish minutes, the sweet hum of electrical currents could once again be heard on the plane. Fans came on, seat belt signs lit-up, and the P.A. system? It still squawked. Finally, at about 2pm, after sitting on an un-moving plane for about two and a half hours, Dad and the other passengers were asked to leave their seats and go back inside the terminal. An hour later, they were told the plane couldn't be fixed that day. Then they were herded into a line to receive motel and food vouchers. Still carrying his loaves of bread, Dad was shuttled to the Westin hotel for the night. He received a 15 dollar voucher for supper. The cheapest item on the hotel menu that evening was 25 dollars. He should have just eaten the sourdough."