wrenched open

She wrenched open doors and marched along corridors with Harry trotting miserably behind her. (Harry Potter and the Sorcerer's Stone)

When I see the word, wrench, I imagine the scene of this:
[WR]
“to give (something) a sudden or violent twist or pull esp so as to remove (something) from that to which it is attached: to wrench a door off its hinges”

So, it’s not easy to picture the sight. Would you explain ‘wrenched open’?

The action is right: it's the accompanying word that distinguishes them. Wrenching is taking something by a violent pull; wrenching is the same general kind of action, but it results in an door.