Have new iMac - don't install Firmware Update!
"My" genius concluded the iMac borked by the Firmware Update could not be repaired and since it was brand new arranged a swap, sending me home with a new one. He said at this time Apple did not have a repair.
That may be because mine had the EFI Firmware password set.
My recommendation, if your iMac is working, is to NOT install the firmware fix until Apple fixes the fix!
"My" genius concluded the iMac borked by the Firmware Update could not be repaired and since it was brand new arranged a swap, sending me home with a new one. He said at this time Apple did not have a repair.
That may be because mine had the EFI Firmware password set.
My recommendation, if your iMac is working, is to NOT install the firmware fix until Apple fixes the fix!