How to unblock a smartphone with NMS installed

I recently bought a Honor 6 and installed Norton Mobile Security from Google Play - it was a free trial version. 

I installed NMS by wifi (I haven't got the SIM card yet).  I don't recall being prompted to register the NMS, and was able to use the phone for several days on wifi.

I received the SIM card today and inserted it into the phone.  Now the phone got stuck at the "Unlock device" screen, asking me for the Norton PIN.

On my Norton account https://mobilesecurity.norton.com/fr/Product/Dashboard, the "My devices" list is empty.

Any help to get me to unblock my phone is appreciated.