An entertaining and informative article by Douglas Alder about getting out of a locked screen on FileMaker Go:
FileMaker Go has a great new features called ‘Reconnect to Server’, which helps keep your database connection open if your iPad/iPhone falls asleep or your WiFi connection gets dodgy. This great new feature can become a problem if your solution sends the user to a layout from which there is no return. Obviously the first step as a programmer is to not let them get stuck — make sure there is an exit strategy for all layouts — that said, mistakes sometimes happen. I found a couple of solutions that may help if your users get stuck.
One solution is straightforward, the other is nuclear. Read the whole thing.