Hello Graham,
Thank you too. Mine is a '98 model (so definitely similar) and I've also heard/read that there are problems with the immobilizer. It's strange that it briefly starts and then shuts off. Apparently, there's also a module for the immobilizer that completely disables it. But that costs €200. That wouldn't be a problem if it worked afterwards. If not, it would be a lot of money for nothing. So your tip is a good starting point to test if anything changes. Thanks