Water not heating/ tablet not realeasing

I have a Bosh Dishwasher Classixx “SG53C12UK/01” and have an intermittent fault where the water does not heat up, and / or the tablet door is not released. This appears to happen when on a delayed start rather than immediate start.
Can you advise on the reason for this?

Possible the problem is a bad control board. We are not able to provide more accurate advice because this is UK model.

Gene.