Ball to the wrong team
 

I'm R (not that it means anything, it's just how the game was assigned. I'm a 1st year HS official, I think my partner has 2 or 3 years under his belt). I am trail, partner is lead. Second quarter with Team A in their front court near the basket. A1 throws to A2, pass is deflected OOB by B1 at the end line about 1/2 way between the basket and the corner, .9 on the clock. The score was 20/21 in favor of Team B.

Partner administers throw in, but for some reason gives it to Team B. I don't notice and in the blink of an eye the ball is inbounded, B1 heaves it and time has expired (no basket).

Team A coach tells me what happened, I confirm it with my partner. He acknowledges that he saw the ball come off of B1 and go OOB; he doesn't know why he gave the ball to Team B.

Coach A wants .9 put back on the clock and the ball for a throw at the end line.

I told Coach A that she is right, her team should have had the ball, but it's a non-correctable error and a "do over" isn't allowed. I get a "that's horrible" and Coach A and company march off to the locker room for half time.

Would anybody else have handled it any differently?

As far as the correcting the situation, there isn't anything you can do to correct that aspect of the play.

The more important element of this situation is good communication. Good mechanics as far as the initial signal giving the ball to A is a starting point. Additionally eye contact before the inbound to make sure everybody is on the same page. Otherwise you did well.

Handled the screw-up by the book. You rightly took some grief from the coach. All you can do is admit that you goofed and move on.
Once the ball is touched inbounds, there's no fixing this mistake.

That's what I have as well.

devil's advocate....I changed 2nd quarter to 4th quarter in above OP. Would anybody still go by the book?

What other choices do we really have other than to follow the rules? Make up our own rules? Never a good idea.

Rule 2-3.

Yes.

2-3 deals with points "not specifically covered in the rules." This one is covered.

I guess that it would be very hard to get wrong anyways.

Most decent coaches for team A would have a timeout to set up a last second shot and then raise a stink if you handed the ball to B1 after I just drew up the game winning shot for A2. ;)

Although I can see it going bad in OP easy enough.