Originally Posted by
flightrisk
I believe you only need to hold the power button for 10 seconds, at least that's what an FA taught me once. It's almost always worked for me, though I'm guessing it was primarily on 738s. The most typical problem it resolved would be when the movies option is missing from the carousel menu.
Occasionally there are glitches that cannot be resolved in this way and require the FA to perform a different type of reset from the galley.
I can report that this is the case on the 321's as well; holding down the power button for what seems like forever will completely reboot the device....