BMW 7 Series - External rear door handle broken with child lock on

[MrMustard]

Hi,
Has anybody found a way to take the child lock off with the rear door closed please? Whilst the external handle is broken and will not open the door I am confident the internal handle would with the child lock off. (I know because when I was trying to work out why the external handle wouldn’t work I foolishly switched it on after having just opened it from the inside! )
Many thanks,
Mike