Does the fan run when you try to ignite the oven ? If not I would go for pcb board,failing that i would be doing an insulation check, also worth checking polarity on the socket its plugged into I’ve had them do all sorts of weird things when there’s a neutral fault, failing all that give stoves a ring and they might put you through to there guy in technical I’ve spoken to technical before
Everything works all be it briefly, Insulation and polarity was my first port of call, sure it`s something simple but I hate just throwing parts at things.
Give stoves technical a ring they are pretty good,only 1 other thing I would suggest checking is the micro switch on the valve/thermostat, I assume you have checked continuity on element and safety stat,and that you are still getting 240v to oven/ timer ?
Can close this post, Customer believes it`s unprofessional of me not to have the fault codes and she has been waiting 3 days, I politely told her to be on her way.