If you get knocked back and down into opponent's endzone...

[nick_nameless]

while holding the ball, do you score a TD?

I assume you would as the sequence is that you get pushed back and then knocked down, so you would be holding the ball "at any point on your opponent's turn", but I can see players making the other side of the argument if it ever happened. It would seem to me based on the wording that a TD would be scored, the rules for breaking armor and causing injury should be applied, and then the drive would end.

[Gumbo]

Nope, the player is down and its not a td. Has to be in control of the ball.

[Dr. Von Richten]

No.

You have to be standing and with the ball in your possession to score a touchdown. And then you score immediately.

So:

pushed back: yes
pushed back on the first block of a player with frenzy: yes
pushed back & knocked down: no
pushed back & ball stripped: no