Ramming speed

[Mark]

Even though BY ramming, he damaged the auto-destruct initiator

[Lt. Staplic]

no he didn't.
the thing plays out like:

He orders troi to initiate the thrusters.
We see the Enterprise start forward
Shinzon realizes what's happenning and orders a full reverse and tilts the ship
Then we see the two ships hit eachother, we see close ups and flashes aboard each ship as they tear into each other.
Pause (Presumibly it's here that the captain initiates the Auto-Distruct)
See Shinzon, and he orders a full reverse.
The ships tear at eachother again as they seperate,
once free, Picard orders the computer to stop the auto-distruct.

[Captain Seafort]

No, Mark's right - Picard tried to activate the auto destruct, but it was off-line. Probably knocked out by the ramming stunt.

[thelordharry]

It's the truth man! Even I remember that

[Mikey]

"Starfleet R&D - where we can't even blow up our own ship if we wanted to."

[Sionnach Glic]

I find it ridiculous that, whenever the auto-destruct fails on any TNG+ ship, they're completely unable to destroy the ship. Hey, geniuses, why not shoot the fracking warp core? Or shut down the safeties, or shove a surpluss of anti-matter in, or detonate the ship's torpedo complement, or use the phasers to shoot your own nacelles, etc, etc, etc.

[Mikey]

Or overload the injectors, or anything. That always boggled my mind.

[Captain Seafort]

Spock and Scotty came up with an improvised plan to destroy the E-nil as it was passing through the Galactic Barrier in "By Any Other Name", but by TNG such innovation seemed to have gone out the window.

[Lt. Staplic]

but if the auto distruct had already gond off line, why did he have do deactivate it?

[kostmayer]

I always love the disappointed look on the Captains face when the autodestruct doesn't initiate.

[Captain Seafort]

He didn't deactivate it. The sequence was:

Enterprise rams the Scimitar
Scimitar reverses away
Picard orders auto-destruct
Computer tells him the auto-destruct is off-line

The first time it was even mentioned was after the ramming, by which time it had been wrecked.

The relevent part of the film

[kostmayer]

What happens if you activate the Autodestruct whilst its offline, and then some enterprising young engineer repairs it later?

[Captain Seafort]

I assume nothing would happen, other than you'd be able to activate it, as it wouldn't have been activated in the first place. It'd be like typing a long word document while the computer was switched off - the document wouldn't magically appear as soon as you turned it on.

[kostmayer]

But if you try to print the document with the printer off, and then turn the printer on, it will normally print.

[Mikey]

And a doughnut without a hole is a danish.

If it's offline, then it's offline for receiving an activation code as well as for actually blowing up.