On some of their ovens there is a secret key sequence (like game cheat) to get the buttons working again. Every 6 months you need to do this otherwise pay for a service call to do this. Or have a defunct oven.
But it is not public info they have released (but had been leaked on YT)
So they have software with a bug and a workaround they won't tell you about. Ideally they should recall these ovens and pay for a replacement install.