Backup locked Z3 Dual

My mum's Z3 dual is locked with pattern and she can't remember it. My Xperia is not activated, neither is USB debugging. I tried using Android Device Manager and it locked the device, but there is no text entry field, and when I press back it still asks for the lock pattern. I know I might have no choice but to wipe the device, but I just want to know if there is a way I can save my data.
Software version is 5.1.1