I had a problem with my NFC Unlock app not letting me "in" after switching to Airplane mode.
On Airplane Mode that NFC transmitter is as disabled as is any internetconnection so neither NFC unlock nor Gmail unlock will work.
I have read that some saw now other way then factory resetting their device.
I was also going to do that when I stumbled upon a promising item in the Recover Menu: "Wipe Cache"
So I though what the heck, before factory resetting the device I might as will try wiping that damn cache and see what happens.
After wiping the cache, I booted and android went through all those apps, and then showed the unlocked launcher for long enough to switch off the airplane mode, just before the unlock app was loaded and immediately locked the screen again. Only this time I could unlock it normally :P