most induction hobs have power board and control boards power boards often do 2 rings maybe 3 at a push so if a power board failed i would expect only 2 rings to be affected
you say in your case all rings have failed at once so it sounds like a control board problem. i would need the complete Enr number to get a part number which should be underneath the unit
Beware, A lot of these types of boards need configuring, which means manipulating the controls to link the boards together. This info will be very difficult to find so it may be you would have to get Neff to fit it
Dave