Modern Vespa

Hi team,
This is my first post on here but I've been using this forum for about a week to try and find a possible solution to my problem.
I have bought above Vespa with damage to ignition and seat lock after theft attempt (unsuccessful) and the owner was not able to start it after that. I have replaced both locks successfully. Both original brown key and blue key are there, brown key however can not be recognized (3 flashes on LED) but I was able to start with blue key taped to immobilizer antenna (new style 3 pin). There is no other way to get it started except for when the old key is taped to the antenna, wouldn't recognize it in ignition either.
I have tried measuring the Ohms in the antenna, I get Megaohms between all pins but then I couldn't find any info on what's happening inside. Obviously can't do the same as with the old style 2 pin ones that should measure around 9 Ohms. There may be switches in there that aren't activated when power is off? Does anyone have any info on the 3 pin antenna? I think this may be the problem. I couldn't find a wiring diagram on the 3 pin antenna either, so any help and or pointers would be much appreciated. Thanks team

edit: I'd like to run a few more diagnostics before committing to buying a new antenna, these are like $100 US + and not readily available here in New Zealand

Normally the dealer has to reprogram the ECU if new ignition switch is installed, little hack below might help.

https://www.youtube.com/shorts/-1kQ_vFXnY4

Thanks for that, I have seen that video. I have transferred the chip from old master key to the new master key. Immobilizer didn't recognize the master chip even before I changed the lock..

I have "solved" this myself, I will post what I have done in case anyone ever comes across this. It turns out the master key must have been a dud, which is a shame. The transponder chip in the working key was successfully identified as a service key as the immobilizer LED did one 0.7sec flash before it turned off (master key does a 0.7sec flash followed by two short flashes). So I will get my only working key cloned just in case I lose it.

Turns out the antenna works fine, I've cleaned out the contacts.