how do i get serial number from ford 5000c stereo cassette without taking u?

i need serial number for ford 5000c stereo cassette but dont wana take out unit from dash. i dont have manuals or service book. unit in 2008 57reg fiesta. ive tried hold down 6 and press 2 but loads of numbers and letters flash through in a sequence that looks like dates and volume contorl levels etc nothing looks like a serial number? help! mail me pls saffron_bingley@hotmail.com