Superb Mk2 Estate L&K, boot not opening

2014 mk2 Skoda Estate L&K.

The boot won't open from the outside either with the key or the button to open the boot.

I can open it from the inside from the emergency release and then the motor lifts and closes it using the boot buttons.

All lights working also.

Why won't it open?

My question is does anyone know what part I most likely need to replace?

lock unit?

and if i need to replace the lock/other, will there be any effect to central locking, coding etc...?

Many thanks