M5-620 Upgrade Failed And Seems To Be Bricked --- any help?

Radio was fully operational on version 3.22.1.0.   Decided to upgrade it to version 3.22.8.0.  Uploaded aredn-3.22.8.0-ar71xx-generic-ubnt-rocket-m-xw-squashfs-sysupgrade.bin, radio rebooted but never returned.  Power and ethernet were never interrupted during upload.  Tried multiple resets but radio is not issuing DHCP and it's IP address doesn't appear in the ARP table.  Radio seems to reboot when reset but eventually the radio's LEDs show (left to right) #1=grn, #2=off, #3=off, #4=red, #5=grn.  LED #4 does slowly flash red then off and back to red.  Tried changing to static addressing using the same addresses working under 3.22.1.0 but this too failed.   Even tried IP address 192.168.1.1 without success.  As a last effort, I put the radio into TFTP mode.  Tried to reinstall the factory.bin software to the radio's IP address but the TFTP failed - timed out.  

Any suggestions to bring the dead back to life?  I have other radios that I have successfully upgraded to version 3.22.8.0 so I'm pretty confident that I didn't goof on this one.

Hoping someone can help me on this head scratcher.
Thanks,
Wayne / WA7NE