Safety lock on Neff hob

I have a Neff T4344N0/08. I cannot stop all four hobs flashing - ie: I press the 'on' button all four flash, I then choose which one I want to use plus the number but they all keep flashing instead of stopping after the usual three or four. Please help - have I pressed something I shouldn't, perhaps a child lock?

I'd be grateful if anyone has sorted this problem out - my Neff hob has been nothing but trouble since it was installed - it turns itself off when I'm only using one of the five hobs, has ruined Christmas dinner for the last three years and had to have something extra installed by an engineer shortly after installation as he said Neff had identified a problem with the electronics. Mine has now shut itself off apart from the security light flashing so I can't use the hob at all. Looks like something from the oven for dinner today. Very disappointed with the hob.

Have power to the hobs but no heat at anytime. it some times makes constant buzzing noises and after switching it off fuse pops out.

To deactivate mine is as follows (copied verbatim from the manual)

to deactivate the childproof lock is the reversal of setting it -
turn all four hotplates to setting 2
turn off all the hotplates in order from right to left
touch the main switch for at least 5 seconds, once the five seconds is up you will hear an accoustic noise.
it is now deactivated

to turn it on with the childproof lock on you have to touch the main switch for 4 seconds