I have Ford radio code but cannot lock in. I am on try 7?

I have a temp Ford radio in my Ford Fiesta (N reg). I have the code (1705) but cannot lock it in. There is no select or AS button & pressing '5' keeps returning to the 'Wait 30 minutes' option. I am on try number 7, I would appreciate advice. I am changing my car in 2 weeks but would like some music in the meantime. I can't get radio out to get serial No. Buttons are 'Bass/Treb', 'Fade/Bal', 'TA', 'AM/FM', 'Menu', 'seek' (with forward & back arrows) and numbers 1,2 3,4,5 & 6. Can anyone help please?