Bosch Serie 4 Condensor Dryer -over heating

WTN85280GB/01 FD9804

Reported fault. Over heating indication reported by user.

This is a quite heavily used machine in a school cooking classroom.
I have checked everything I can. Despite it’s age and useage. It’s extremely well looked after.
I stripped and cleaned what I could and only got a handful of lint from inside the condensor housing.
The condensor itself and everything else very clean. Very clean inside as well. Had the back off to access the heater.
It’s just clean.

Senor inside the dryer clean.

Can anyone help with the test sequence and accessing the fault code?

Thanks in advance
Steve