Hi Tony,
I can sympathise for sure.
I had an expired battery and after several jumpstarts and a replacement, the immobiliser decided to kick in ( sort of ! ). Just what you need when you've already suffered starting problems - it just confuses things !.
Eventually took the battery off, and left off for nearly 48 hours.
I think this cured the immobiliser probs ( reset ).
Talking to a few folks, and reading some posts, it sounds like some immobilisers can be a double edge sword, equally capable of punishing the genuine owner as well as the would be thief !.
For the most part, they never get put to action, and are hailed as successful when someone does the dastardly, but, get a flat battery and have a few jump starts, electrical probs.....
Surprising how many genuine owners have to pay £30-40 to get someone out to reset the system.
Hope all is well after the fix !
Ian