Thank you for your post.
There are two possible options.
First, the client may have used an upwards three-finger swipe on the layout to hide the Menubar. Use a downwards three-finger swipe on the layout to reveal the Menubar.
The second option may have been caused by a script that hides the Menubar. If the Lock option wasn't used, then you can still use the downwards three-finger swipe to reveal the Menubar. If the developer used the Lock option when hiding the Menubar, then you will have to use a script to Show the Menubar.
Let me know if you need additional clarification.
I'ld recommend to place a button somewhere with script
In the past, we used this to quit FMGo in a manner that FMP Host/Server would reset the connection. Otherwise, when a user quit FMGo by the Home Button, you couldn't quit FMPro since it claimed a device would still be connected.
This isn't necessary anymore with FM 14 since FMPro will reset the connection after >2Min. Idle time. Though I recommend users to quit FMGo via the Homescreen Button.
Yours is one of many cases where a Exit Application Button is still recommended.
The Exit Application step leads you NOT to the Homescreen, but to the Launch Center as you ask for.
(not sure for how long this' gonna work since there are many feature requests asking to have Exit Application leading straight to the Homescreen, NOT Launch Center)
I ran into this at one point as well. The menu bars were locked hidden with no exit button. The only way to get out was double tap home and swipe up on FMGo, then restart the FMGo app. Bad news. This is one area where you need to be concious of the layout navigation design.
Since FMGo is storing your last Layout position for next launch, you can build a bad navigation script that leads you into a dead-end (a empty layout, for example) were delete and re-install FMGo is the only way to get out (reset cache).