Smeg oven SA 392 EB - technical difficulties

Question

We recently purchased an apartment with a Smeg oven SA 392 EB installed (probably in the 90s). For some strange reason the oven has stopped heating. The fan works fine as do the elements. The yellow/orange light comes on as if it is heating when the cooking method is set to 'off' but then switches off again when I select a fan/grill setting. Any ideas? The symbols are completely non-sensical. Maybe I've accidentally selected a timer setting. But we have been playing around with lots of different settings with no result.
Any help greatly appreciated.
Desperate P.