Malfunctioning locks seem to be common with Hondas that have laser-cut keys. After lots of research and tutorials on repairing the ignition cylinder I was able to remove the cylinder, extract the worn out "wafers", and lo and behold, the key would turn the cylinder in the barrel while both were still separate from the car (in my hand). But upon reinserting the cylinder and barrel into the ignition assembly, the key no longer turns.
It strongly resembles what happens when the steering wheel is locked, but I'm familiar with that problem and even when relieving the pressure on the steering wheel, no luck turning the key.
I'm fairly certain the barrel only goes back into the ignition one way, so I haven't put it in upside down, and it's not a transponder or battery problem, because the key should still be able to turn past the zero position with those issues.
Does anyone have any ideas, please and thanks?