Galaxy S5 :: Fingerprint Scanner Not Showing And Backup Password Not Working - Locked Out Of Phone

My wife turned her Galaxy S5 on yesterday, slid her finger across the scanner to open the phone and it came up with the print not recognised message (as it has many times before). This time however, it did not allow her to scan her print again. the screen changed and asked her for a back up password, not a problem as she has done this a fair few times too, it just seemed strange that it only allowed one stroke of the scanner before asking for this. We have tried her back up password many times (and any other password we could think of) but the phone will not unlock, nor will it return to the normal lock screen and allow her to try her print again.

We have logged onto Android device manager and tried the lock screen hack (to obtain another password) but it just tells us that the screen is already locked so another password is not necessary.