Error code on the cook top.

Question

Hello,
If you could please help it would be appreciated. We just moved into an apartment with a Schott ceran cook top which is new. And it worked yesterday, but today all 4 burners when we try to use it give an code like a U with a line under the U. And none of the burners will work and we already read the manual but no code to help us. I hope you can please.
I look forward to your reply.
Many thanks,
Jackie