The canopy became stuck in the down and locked position and could not be opened manually after the pilot cycled the mechanism several times, following a pre-flight warning that the canopy was unlocked.That "cycled the mechanism" bit, that sounds like he pushed a button several times -- like it's an electronic or electro-hydraulic "manual" release.
For purposes like this, you *don't* want a bunch of thingamajigs that can decide to want something different than what you tell them to.
What you want for your *manual* release, is a good old *purely mechanical* thing -- where you can see how the handle you turn is directly connected to a hook that goes into a latch.