Oven dies during pyrolytic cleaning

I have a Whirlpool pyrolytic oven (model AKZ511) that is about 2.5 years old and has just died mid-way through a pyrolytic cleaning cycle. This first happened about 4 months ago and was eventually ‘cured’ at great expense by an engineer replacing the control unit plus a faulty grill heating element that wasn’t earthed correctly. Today I have used the pyrolytic function for the first time since the repair and the oven has died again – no power whatsoever, not even the clock, and the oven door is locked. One other thing I noticed today was that the exterior of the oven was VERY hot – I do not remember this being the case in the past.

Can anyone offer any advice on what the root cause of this recurrent problem might be? I have arranged for an engineer to come out again but I don’t really want to go through the same process as before only for the underlying fault to not really be addressed.

Many thanks in anticipation.