Prompted for Password on Fon 460i

I am being prompted for a password on my Fon 460i.   I think that the phone has failed as I have never seen this prompt before.

The prompt appears after a reboot and never progresses any further.  The complete prompt is:

Bootc Start (IP8820E)

Enter Password:

I have a FortiVoice FVC-70D4 switch.  FW is 5.1.0 build 77

Any help would be much appreciated.  I did not see anywhere else to post this thread.