This is how Sentinel Prime's betrayal goes in My Little Pony Transformers: Dark of the Moon.

[Ironhide and Rainbow Dash are under attack]

Twilight Sparkle: Ironhide, protect Rainbow Dash, get her inside.

Ironhide: Consider it done.

Twilight Sparkle: [to Moon Dancer and Captain Thunderbolt] Look, we also have to get Sentinel to safety. Cause he's the key to the pillars.

Sentinel Prime: Indeed I am. What you must realized, my Autobot brothers is we were never going to win the war. For the sake of our planet's survival, a deal had to be made... with Megatron.

[Sentinel fires at Ironhide twice]

Captain Thunderbolt: Get back!

Ironhide: What have you done?

Sentinel Prime: I hereby discharge you from duty.

[Sentinel fires at Ironhide before he falls to the ground]

[Soldiers, guards, the Autobots, Mane 6, Spike, Starlight, Trixie, Discord, Thorax, and the Canterlot warriors fall back as Sentinel fires at them]

Rarity: Bee!

Captain Thunderbolt: Get back!

[Bumblebee returns fire]

[Moon Dancer and Adagio return fire]

[Sentinel fires at the soldiers before driving off]

[Sentinel goes inside]

Captain Thunderbolt: Rally all PHOENIX forces back to the base!

[As Sentinel heads into the base to retrieve the pillars, Rainbow Dash uses her friendship magic on the dying Ironhide, removing his cosmic rust]

Major Malfunction: I've got him. Help the others.

Rainbow Dash: But who's gonna repair the damage.

Major Malfunction: Two of my students.

[He shapeshifts into Brawl and hauls Ironhide away]

[Inside, Celestia is approaching when Sentinel blasts a few vehicles]

[Celestia and her guards run for cover]

[Sentinel destroys some vehicles]

Princess Celestia: Hey, Sentinel, what is going on? What do you think you're doing?

[He stops for a moment]

Sentinel Prime: I'm a Prime! I do not take orders from you!

[Thunderbolt and his squad arrive]

Captain Thunderbolt: Move! Move! Move!

[Sentinel continues his attack]

Sentinel Prime: Now, return what belongs to me! [destroys more vehicles]

[More ponies try to get away as Sentinel drives away with the pillars]

[Optimus drives up and transforms to robot mode and looks around in shock and sadness]

Princess Celestia: Yeah, take a look around, Optimus! This is all on you!

[Twilight looks at Celestia in disbelief]