I've just bought a second hand unlocked 6600 from Ebay. When I've put my sim card in it says "Sim card not valid". I know that the phone is unlocked as I have entered the code from unlockme.com. In the manual it says that the lock code has to be entered when a new sim card is installed. However, it's not even giving me the option to input this code - I've tried to follow the instructions but it says to press the blue button underneath the green "send" key but this doesn't do anything. I've tried this with the sim card in and without the sim card.
Please help as this is a Birthday present for someone!