The clock stays low on my board as well after failing to communicate (I force a failure by not being in download mdoe). This isn't a problem.
What do you mean the data value doesn't make sense? What is the value?
When I'm not in download mode the FTDI chip sends an address 0x4 (8 bit address format i.e. RW bit is included) and the aduc7023 doesn't ACK the address. Could you send a scope plot of that? But basically if that address isn't acknowledged by the ADuC7023 it's because it's not in download mode. If address 0x80014 contains some value other than 0xFF.. you won't be able to enter download mode.
When I'm in download mode that address is ACKed and the rest of the communication happens and the ID string is returned by the ADuC7023.
Regards,
Alex