There are some suggestions here:
In particular:
"The tech at the genius bar had some useful info. He said the restoration method now uses the Ethernet port. He confirmed the bootloader will try to redownload the OS via the Ethernet port. However he didn’t clarify if this was downloaded from the Internet or from the Apple Store’s LAN servers.
He plugged a Cat6 cable into the GigE port, unplugged the power cord, counted to 15, then plugged the power back in while holding Menu + Home on the remote at the same time."
Note that this didn’t work for the poster but might be useful for others.