Once a try is released, the ball does not become dead until
- the try ends
- a player control foul is committed
- the offense commits an elbow-swinging violation.
I think that's it. I also thought of BI/GT is committed, but that would also end the try. So I think I have it covered.
Any other kind of foul does not cause the ball to become dead; the horn does not cause the ball to become dead.
In your situation, you'd still assess the technical foul, obviously; count the basket; then award the FTs and possession to the offended team.