You should charge something for the time involved in the firmware update flake-out. It's not his fault, for sure! But it's not your fault either. How is not charging him fair to both you and him?

You could make the point that this is the state of the art ( = "how things are right now") and he's welcome to sit with you and watch supposedly wonderful equipment, whether bought by him or you, NOT do what it's supposed to.

I lost out once with a client who was an oncologist. I simply could not make his HDMI situation work and he didn't want to pay for the time it took me to ultimately get it going. I yielded. I should have asked him, "Uh, Doc, when you try an oncology treatment with a client, and it's the same cancer you've seen before and you're using the same treatment you've used a hundred times, but it doesn't work: don't you charge for the work you did on the way to getting the right solution?

Charge him half the time it took to do the first firmware update(s), and of course full rate for the successful one.