I have a CCR600 radio in my Vauxhall Zafira, I successfully removed and replaced it once using the codes supplied and following the instructions in the manual. However when I try and set it up now, I press and hold the AS button, turn on the unit and get a tone. The display shows "10 _ _ _ _" as I would expect, but before I can enter the full code and re-press the AS button, the unit turns off. any idea?

HTB, May 2010