standard vauxhaull corsa stereo

Hi, i got a problem with my stereo in my corsa, after having the battery
removed the stereo now says safe!
it wont respond to having the AS button held in and the usuall attemps to
get the code in so i got a new one that i witnessed working.
after installing it i still have the same problem. Does anyone have any
idea whats wrong?
could the switch live from the ignition be missing?
and has anyone got any wiring diagrams so i can check the multiplugs?

many thanks for any help
Robs