Glad to hear you got it started.
It is possible that your alarm's memory is conflicted.
I was also able to start the XP by using the 'micro' button under the dash, about 3" back on the wiring of the red Valet button.
That worked but was not a permanent fix.
Using the alarm reinitialization procedure as outlined above should reset a Ford System 3 or 4 Security System back to the default mode, so it will work as intended.

I went a step further and put a on/off switch inline with the Siren under the hood.
If I need to troubleshoot this security system again at least I can shut the d**n siren off while I work on it.
I think I'm going to crawl under the dash and take a picture of the Valet button and the 'override' micro switch.
I'll post it here when I do.