What to do after failed shot clock reset?

[Lotto]

Here's a situation that came up yesterday that I'm not sure I handled correctly. HS girls varsity, played under NCAAW rules (with a few state modifications):

A1 shoots the ball, which glances the rim with 9 seconds on the shot clock. A gets the rebound. I notice that the shot clock was not reset a couple of seconds later and am about to blow the whistle, but A2 is about to shoot so I let that shot go up (since if it hits the rim or goes in, problem solved). The shot misses the rim and the shot clock horn goes off before anyone gains control. I have definite knowledge that the shot clock should have read 21 at that point, but there's no team control. I go to the arrow, which points to A, so I give the ball to A with an AP throw-in and 21 seconds on the shot clock.

Should I have blown the whistle before A2 takes here shot?
If I blow the whistle before A2 takes her shot, what is the proper next action?
If I blow the whistle when I did (after A2's shot, shot clock down to 0, no team control), what is the proper next action?