Thanks for all the advice. Fingers crossed it's an easy fix.
I'll post as soon as I know something because I can't imagine I'm a one-off.

 

It's electric? Interesting. So I guess it's part of the security system?

 

Yes - that's correct. It appears to be controlled by 12 V from the central junction box.

 

So did I activate it somehow, or is it a glitch?

 

If by glitch you mean a fault, then I'm sure it is. But whether it is a software or hardware issue - no idea - it presumably could be either. After the 3.0 update I found, rather randomly, that the passenger seat heating and cooling was no longer functional. My suspicion was the seat HVAC sensor had failed, but a full PIVI reboot (engine off) fixed it.

 

Thanks Muppetry - I should know more in an hour or so when the dealership contact me... I hope.

 

@Elektrapops - this may sound stupid .... but try to disconnect the battery for 30 min. Then give it a try again. Maybe it will amount to nothing, but what if ?

 

Big thanks for all the suggestions, and I mentioned them to the dealership. I think they were as interested in what this could possibly be as we were.

I got the car back and this is what they've done:
* They tested in case there was any mechanical damage to suspension, checked voltages and resistances throughout, and all comms sets.
* They then checked the C1CS05A and C1CS05B pscm connectors - they were fine, but the steering was still locked. So they re-connected those C1Cs and the steering then worked, and then they followed up with an update to the pscm software and performed several road tests to check. All seems good.

I guess, basically, it was a reset, as mentioned in this thread. I asked dealer if this could happen while I'm driving. There was a lonnnng pause before the reply "I'm gonna say no". Fingers crossed. I'm attaching a photo of their report sheet for reference.

Cheers

 

"Can it happen while driving" was the biggest question in my mind too. "I'm gonna say no" is not the answer I was hoping for.

 

It is worrying. I'm going to keep a look out on this forum for anyone having similar 'steering wheel locking' issues.