Talisman Electrical Malfunctions Navigation Failure

Sounds familiar. I also own a Talisman, though not the same year. I had similar electrical gremlins and a non-functional navigation. Did you check for software revisions?

I haven't tried that yet. Where would I find the software revisions, and is it something I can do myself? Or does it require special equipment, like messing with the car's 'brain'?

For me it was a software bug. I didn't attempt it myself, it seemed too risky. I'd recommend a workshop visit. They can diagnose it properly and perform a software reset if needed.

Thanks for the advice. I will take it to a workshop. The diagnosis pointed to implausible control unit programming, and the software revision and reset cost 240€. Hopefully, that'll sort it.