iTunes says no SIM card, can't activate. but there is.

iPhone has been working perfectly but went completely flat yesterday. When I stuck it on the charger today it displayed the original multi-lingual connect to iTunes to activate screen instead of recovering. iTunes said couldn't read the phone contents and undertook a restore. Restore went through fine but I'm now stuck trying to activate with iTunes message "There is no SIM card installed in the iPhone you are attempting to activate." The original SIM is in the iPhone though.

I've tried:

- rebooting everything
- activating with a different cable, different Mac and different internet connection
- activating with my wife's SIM in the phone (same account, same carrier)
- confirmed my SIM works fine in my wife's iPhone4
- putting the phone in dfu mode and restoring again

All with no change. First available Genius bar appointment isn't until next Friday. I suspect there's probably a hardware fault and I know the Genius will probably swap the phone out. It's a week away though - is there anything else to try?

Cheers,
Steve.