To start andriod, enter pin...?

Hi, 

I've just bought this brand new unlocked phone from Amazon and bought a SIM separately. I've activated the new SIM and installed it into the phone.

Then I get a black screen with this message 'to start andriod, enter your pin' - well I don't have a pin - I've tried all the factory standard numbers 1111 and 1234 etc but I can't get past this screen - is there a way to get past this? 

Many thanks