Hi, i tried to install 3 CP 521S in a site with UC520.
2 of them upgraded correctly their firmware.
The third got unplugged while downloading the firmware and now it is stuck and displays as soon as it gets plugged in:
"S.O.S. Phone in Recovery Mode".
I found the rec-spa941-5-1-8.exe and the rec-spa942-6-1-3a.exe but i cannot make it work.
Any help will be appreciated.
Check to see the correct 'type' (model) is created for the phone.
Perhaps 'debug tftp events' and Debug Ephone register' to see what's going on.
Sent from Cisco Technical Support iPhone App
Another suggestion which has worked for me with a 524S when the same thing happened to me was to force a factory reset on it, although I have never personally seen a 521S and do not know much about them, so if you can discover how to do it (Maybe someone from Cisco can post the instructions) you can possible bring it back from the dead (Brick mode) and then let it update the firmware properly.