B1593N0GB/07 key sign came up followed instructions to remove ie hold central knob in for 7/8 seconds. Sign went away when I did it, customer used oven ok twice now sign come up again and cant delete it.
Mike
Had a look on the NEFF website and this machine is too old to download a user manual so can’t help with the reset procedure.
It does sound like the child lock is coming on. Could you talk the customer through the reset programme on the phone as you said they have the manual?.
Failing that I can only think the central knob could be faulty and getting stuck on and activating the child lock?.