how do i reset myVeritas 8 alarm after a mains failure?

I flicked the trip switch on my fuse box so i could change some light fittings. The light fittings switch also turned off the alarm. on returning the power to the alarm it sounded. I followed the user manual for resetting after mails failure ie enter code press full (you then get 10 beeps repeatedly) I pressed omit & all zones lit up. I pressed 0 & all lights remain red & the tamper light comes on when i press programe all lights go out & the exit sound starts. on re entering the code the entry/exit sound stops but the unset light remains flashing. On entering the code to set alarm again its back to having to go through the same proceedure again. What can I do to rectify this