How to remove handle from grohe shower handle?

Our shower has a Grohe faucet (I think it is the Arcada model that is discontinued. Last night when I went to turn off the water after the shower it just spins 360 degrees when I turn it and will not "catch" and turn the shower off.

I have had to cut the water off to the whole house.

Now I am trying to take the handle apart to see what I am dealing with an am stuck.

I attached photos. I was able to remove the screw that goes in the center but this black plastic part of the handle all the way to the blue/red markings just spins as one unit. Should it lift/pull off?

There is a hole in the top (shown in one picture) that I thought might have a screw in it but can't see anything. I have tried an Allen wrench and regular screwdriver.

I read that there should be a "set screw" somewhere that takes an Allen or Hex wrench but the spot I describe above is the only place visible and there isn't a screw.

Also read that if there isn't a set screw the handle should just pull off. It does not budge. The escutcheon screws come out but that plate will not budge either – like the handle is holding it down.

Here are the photos. Top three are from the internet of what I think this is (Grohe Arcada). Bottom are where I am now and am stuck.

We are stuck. Any ideas? Thank you in advance.