Has the hob previously been in working order for any length of time? If so.....daft solution I know ..but have you tried putting a fairly warm pan of water on a heating zone to see if it then starts to supply power to the ring. The Miele hobs, like other induction hobs, have a generic fault that after a few years a couple of capacitors in the power control circuit get "blown" and swell making the hob inoperable. Easy fix if you are handy but can cost if you need to call out an expert. P.S If it starts to heat after a warmish pan has stood on it for a while it is a heat sensor problem. They have a fail safe mode that will not let the hob come, on rather than going full on, when they fail.