I've heard that exiting and returning to the capture screen will change your raid boss cp, but that when (if) you catch it, it will revert back to its original cp. So in this case, if you had been luckier, you still would have gotten a 1792. Hopefully someone can confirm this because I've never seen it myself.
As far as catching it, that sucks. Are you doing all their usual tricks? Curve? Golden razz? Otherwise I hope your luck improves this weekend.