LG G2 Not Prompting Unlock Code Screen..

So my LG G2 bricked itself a couple of weeks back and I managed to get LG to 'repair' it and send it back to me, I got it back today and it's locked to Vodaphone (UK) and my SIM is on EE. I need to get an unlock code but unfortunately I can't seem to find a way to enter the code once I get it as the box which usually comes up when a non-accepted sim is inserted is not coming up! How can I unlock my phone to use my EE SIM?

Thank you in advance.